Opinion by Judge THOMAS; Partial Concurrence and Partial Dissent by Judge CALLAHAN.
THOMAS, Circuit Judge:This petition for review presents the question of whether six restrictions on expressive activity promulgated and enforced by two California shopping malls infringe on the free speech rights guaranteed by the California State Constitution and therefore interfere with protected union activity in violation of the National Labor Relations Act (“NLRA”) when applied to union picketing and handbilling actions. We hold that the six rules impermissibly infringe free speech rights and unlawfully interfere with protected union activity.
I
Macerich Management Company and Macerich Property Management Company (collectively “Macerich”) operate as the managing agents for Arden Fair Mall and Capitola Mall (“the Malls”), respectively. The Malls are enclosed, privately-owned shopping centers located in Sacramento, California, and Santa Monica, California. Macerich promulgated a list of “Rules for Public Use of Common Areas” that regulate expressive activity in each mall. Among these rules are the six at issue here:
Rule 1 (“identification ban”): a ban on activities that identify by name the mall owner, manager, or tenants;
Rule 2 (“commercial purpose rule”): a ban on signage and written materials that interfere with the “commercial purpose” of the mall;
Rule 3 (“signage ban”): a ban on the carrying or wearing of signs;
*961Rule 4 (“application requirement”): an application process that requires the pre-submission of written materials;
Rule 5 (“designated areas rule”): the exclusion of exterior areas, including mall sidewalks, from designated areas where expressive activities may occur; and
Rule 6 (“peak traffic rule”): the prohibition of expressive activities during “peak traffic days.” 1
According to Macerich, the general purpose of these rules is to safeguard the commercial activity of the malls, provide shoppers with a pleasant shopping experience, and protect shoppers’ safety.
On December 16, 1999, representatives of United Brotherhood of Carpenters and Joiners of America Local 586 (“Local 586”) distributed handbills at the interior and exterior entrances of the Sears store at Arden Fair Mall, to protest the use of a nonunion contractor to build a Sears store in Roseville, California. Local 586 did not file an application with the mall beforehand, nor did it submit the handbills for pre-screening, because a union representative had been told by an Arden Fair employee that an application was unnecessary. Mall security guards informed the union representatives that they were trespassing and would be arrested if they remained on the premises. When the union representatives refused to leave, mall officials called the police and one representative was arrested. Later, a Local 586 representative filled out an application, which was denied as untimely, incomplete, and ambiguous. On December 21 and 22, 1999, Local 586 representatives went to Arden Fair Mall wearing shirts that said “Do Not Patronize Arden Fair Mall — Unfair to Carpenters.”
On March 7, 2000, United Brotherhood of Carpenters and Joiners of America Local 505 representatives distributed handbills and picketed at Capitola Mall to protest the use of a nonunion contractor to build a new store in the mall, and to publicize an area standards dispute. The picketers left after the police arrived and warned them that they could be subject to citizen’s arrest. Two weeks later, Local 505 representatives returned to Capitola Mall and again picketed the construction site. When they refused to leave, they were placed under citizen’s arrest. On May 3, 2000, Local 505 representatives again picketed at Capitola Mall, this time protesting the use of another nonunion contractor. Four union representatives were arrested. In no instance did Local 505 complete an application beforehand or pre-submit written materials to the mall.
Locals 586 and 505 (“the Unions”) each filed unfair labor practices charges against Macerich, alleging that Macerich had violated section 8(a)(1) of the NLRA, 29 U.S.C. § 158(a)(1), by unlawfully restricting the Unions’ expressive activities, unlawfully threatening union picketers with arrest, and having union picketers unlawfully arrested. The charges were consolidated by the NLRB General Counsel into a complaint alleging that Macerich had violated section 8(a)(1) by maintaining six rules that unlawfully interfere with expressive activity, and by ejecting union representatives from mall property for engaging in protected activity.
A hearing was conducted before Administrative Law Judge Jay R. Pollack, who concluded that Macerich had engaged in unfair labor practices by promulgating, maintaining, and enforcing each of the *962challenged rules, and by ejecting union representatives from mall property for engaging in protected activity. Macerich filed exceptions to ALJ Pollack’s decision, and the Board’s General Counsel filed cross-exceptions.
In 2005, the NLRB issued a decision affirming ALJ Pollack’s decision in part. Specifically, the Board upheld ALJ Pollack’s findings that the identification ban and the commercial purpose rule (Rules 1 and 2) were unlawful content-based restrictions under California law. The Board also upheld ALJ Pollack’s finding that the application requirement (Rule 4) was unlawful when applied to ensure compliance with Rules 1 and 2. The Board further found, contrary to ALJ Pollack’s decision, that the signage ban, the designated areas rule, and the peak traffic rule (Rules 3, 5, and 6) were reasonable time, place, or manner restrictions under California law. The Unions filed a petition for review (Case No. 05-75295), arguing that Rules 3, 5, and 6 are unlawful; Macerich filed a petition for review (Case No. OS-77116), arguing that Rules 1, 2, and 4 are permissible; and the NLRB filed a petition for enforcement of its decision (Case No. 05-76217). The Unions then filed a motion to intervene in Case No. 05-77116. By orders of December 9, 2005, and January 24, 2006, we consolidated the petitions for review with the Board’s application for enforcement, and granted the Unions’ motion to intervene. We now grant the Unions’ petition, grant in part and deny in part the Board’s petition, and deny Mace-rich’s petition.
We review the Board’s decision to determine whether the Board’s findings of fact are supported by substantial evidence in the record as a whole, and whether the Board correctly applied the law. Healthcare Employees Union v. NLRB, 463 F.3d 909, 918 (9th Cir.2006).
II
Section 7 of the NLRA guarantees employees the right to form labor unions, bargain collectively, and “engage in other concerted activities for the purpose of collective bargaining or other mutual aid.” NLRA § 7, 29 U.S.C. § 157.
Section 8(a)(1) of the NLRA makes it an “unfair labor practice” for an employer “to interfere with, restrain, or coerce employees” in the exercise of their section 7 rights. NLRA § 8(a)(1), 29 U.S.C. § 158(a)(1). While the NLRA by its terms confers rights only on employees, the United States Supreme Court has determined that it also restricts an employer’s right to exclude nonemployee union organizers from the employer’s property. Lechmere, Inc. v. NLRB, 502 U.S. 527, 535, 112 S.Ct. 841, 117 L.Ed.2d 79 (1992).
Under Lechmere and subsequent cases, the rights of nonemployee union representatives to access an employer’s private property are based in state law. Thunder Basin Coal Co. v. Reich, 510 U.S. 200, 217 n. 21, 114 S.Ct. 771, 127 L.Ed.2d 29 (1994). Where state common law grants an employer the right to exclude nonemployee union organizers from its property, the NLRA guarantees access only if the union can show that employees are otherwise inaccessible to union organizers, and that the employees’ section 7 rights outweigh the employer’s property rights. Lechmere, 502 U.S. at 538, 112 S.Ct. 841. Where state law grants nonemployee union organizers the right to access the employer’s property, a violation of these state rights will also be a violation of the NLRA. Glendale Assocs., Ltd. v. NLRB, 347 F.3d 1145, 1153 (9th Cir.2003). Thus, the question of whether Macerich engaged in unfair labor practices by excluding the Unions’ representatives turns on whether California state law grants union representatives the right to access private mall property.
*963In analyzing questions of state law, we are bound by the decisions of the state’s highest court. Glendale, 347 F.3d at 1154. The California Supreme Court has determined that article I, section 2 of the California Constitution protects .expressive activities — including petitioning and picketing — conducted in . privately-owned shopping centers. Fashion Valley Mall, LLC v. NLRB, 42 Cal.4th 850, 69 Cal.Rptr.3d 288, 172 P.3d 742, 745 (2007) (citing Robins v. Pruneyard Shopping Center, 23 Cal.3d 899, 153 Cal.Rptr. 854, 592 P.2d 341 (1979)). The California Supreme Court has repeatedly held that “private property can constitute a public forum for free speech if it is open to the public in a manner similar to that of public streets and sidewalks,” and that a shopping center to which the public is invited provides “ ‘an essential and invaluable forum’ ” for exercising free speech rights. Id. at 745, 746 (quoting Pruneyard, 153 Cal.Rptr. 854, 592 P.2d at 341). For this reason, privately-owned shopping centers in California are required to respect individual free speech rights on their premises to the same extent that government entities are bound to observe state and federal free speech rights. Glendale, 347 F.3d at 1154. The California Supreme Court has recognized that this protection of expressive activities on private property is “ ‘broader’ and ‘greater’ ” than that offered by the First Amendment to the United States Constitution. Fashion Valley, 69 Cal.Rptr.3d 288, 172 P.3d at 749 (citing Gerawan Farming, Inc. v. Lyons, 24 Cal.4th 468, 101 Cal.Rptr.2d 470, 12 P.3d 720, 735 (Cal.2000)).
The free speech protection enshrined in the California Constitution is not absolute. Shopping malls may impose reasonable restrictions on the time, place, and manner of expressive activities. Id. at 750 (citing Diamond v. Bland, 3 Cal.3d 653, 91 Cal.Rptr. 501, 477 P.2d 733 (1970)). The level of scrutiny with which we review a restriction on free speech activity depends on whether the restriction is a content-neutral regulation of-the time, place, or manner of speech, or a content-based restriction. Id. at 751. A content-neutral restriction is subjected to intermediate scrutiny to determine whether it (1) is narrowly tailored, (2) serves a significant government interest, and (3) leaves open ample alternative avenues of communication. Id. A content-based restriction is analyzed under strict scrutiny to determine whether the regulation is necessary to serve a compelling interest and narrowly drawn to achieve that end. Id. at 754. Applying these tests, we conclude that Rules 1 (identification ban) and 2 (commercial purpose rule) are impermissible content-based restrictions, and Rule 4 (application requirement) is impermissibly content-based when applied to enforce Rules 1 and 2. We conclude that Rules 3 (signage ban), 5 (designated areas rule), and 6 (peak traffic rule) are content-neutral; but fail the intermediate scrutiny test for reasonable time, place, or manner restrictions.
A
We begin with the Unions’ challenge to Rule 1, the identification ban. The Board held that the rule banning activities identifying by name the mall owner, manager, or tenants was identical to the rule we held to be unlawful in Glendale.2 In Glendale, we began by determining whether the rule was content-based *964or content-neutral. 347 F.3d at 1155. Speech-regulating rules are considered content-neutral when the rules are not related to the subject or topic of the speech. Id. (citing Ward v. Rock Against Racism, 491 U.S. 781, 109 S.Ct. 2746, 105 L.Ed.2d 661 (1989)).3 Rules are generally considered content-based when the regulating party must examine the speech to determine if it is acceptable. Id. (citing Desert Outdoor Adver. v. City of Moreno Valley, 103 F.3d 814, 820 (9th Cir.1996)). In Glendale, we determined that a rule prohibiting literature that included the name of a mall owner, manager, or tenant was content-based because the mall would have to review the literature to determine if it included an owner’s, manager’s, or tenant’s name before approving the literature for distribution. Id. at 1156.4 The same analysis applies here: the identification ban is content-based because Macerich would have to review the content of speech and literature to determine whether the speech violated the ban by naming a mall tenant, owner, or manager.
Because the identification ban is contenUbased, we next examine it to determine whether it survives strict scrutiny. Id. “Content-based regulations receive strict scrutiny because ‘content-based restrictions are especially likely to be improper attempts to value some forms of speech over others, or are particularly susceptible to being used ... to distort public debate.’ ” Id. at 1155 (quoting City of Ladue v. Gilleo, 512 U.S. 43, 60, 114 S.Ct. 2038, 129 L.Ed.2d 36 (1994) (O’Connor, J., concurring)).5 Content-based restrictions *965are presumptively unconstitutional; a content-based restriction will pass constitutional muster “only if it employs the least restrictive means to further a compelling interest.” Id. at 1156 (citing R.A.V. v. City of St. Paul, 505 U.S. 377, 382, 112 S.Ct. 2538, 120 L.Ed.2d 305 (1992) and Frisby v. Schultz, 487 U.S. 474, 483, 108 S.Ct. 2495, 101 L.Ed.2d 420 (1988)). The burden is on the regulating authority to prove that the restriction is justified without reference to the content of the speech. Id. (citing Rock Against Racism, 491 U.S. at 791, 109 S.Ct. 2746). Courts have consistently struck down restrictions based in hostility or favoritism towards particular messages. Id. at 1157-58.
In Glendale, the mall argued that its ban on the naming of an owner, manager, or tenant served its interest in ensuring that normal business operations were not disrupted. Id. We held that this stated interest was belied by the fact that the mall made an exception for speech promoting primary boycotts of mall tenants, speech that was likely to be the most disruptive of normal business operations. Id. at 1157. We also held that the rule was untenable because it was motivated by hostility towards messages that might adversely affect business. Id. at 1157-58. We stated, “[i]n restricting such critical speech about their tenants, owners, or managers,[the] rule contravenes the purpose of California free speech protections: the preservation of discussion of issues even when they are contrary to a regulating party’s belief or interest.... The California Constitution does not permit censorship of contrary ideas.” Id. at 1158.
Macerieh asserts a similar interest here. Susan Valentine, Senior Vice President of Marketing for Macerieh, testified that Macerieh adopted the identification ban to protect the “good name” of the mall and its tenants. This stated justification exposes Macerich’s hostility towards messages critical of the mall or its tenants. Because free speech protections were designed to protect critical speech, we cannot find the suppression of critical speech to be a compelling interest. We find that “[t]he Mali’s purpose to maximize the profits of its merchants is not compelling compared to the Union’s right to free expression.” Fashion Valley, 69 Cal.Rptr.3d 288, 172 P.3d at 754. Macerieh has provided no justification for the identification rule that does not reference the content of the speech. We therefore find that Rule 1 (the identification ban) does not survive strict scrutiny.
B
The same analysis applies to Rule 2, the commercial purpose rule. We begin by analyzing whether the rule is content-based or content-neutral. Rule 2 prohibits signage and written materials that interfere with the “commercial purpose” of the mall. As with the identification rule, this rule requires that the regulating authority examine the content of the written material to determine whether it complies with the rule. Like the identification rule, the commercial purpose rule is content-based.
Next, we address whether Rule 2 survives strict scrutiny. Valentine and Carmen Lytle, Arden Fair’s General Manager, explained that the commercial purpose rule was intended to eliminate written materials that would financially damage the mall or its tenants. The Board concluded that the purpose of the rule was to “place restrictions on the content of the message so as to limit any negative publicity and not hurt sales.” Rule 2 is entirely motivated by hostility towards messages critical of the mall or its tenants. Macerieh offers no content-neutral justification for the rule. Therefore, the commercial purpose rule cannot survive a strict scrutiny analysis.
*966Our conclusion is supported by the California Supreme Court’s recent decision in Fashion Valley. In Fashion Valley, the California Supreme Court analyzed a mall rule that prohibited speech “[u]rging, or encouraging in any manner, customers not to purchase the merchandise or services offered by any one or more of the stores or merchants in the shopping center.” 69 Cal.Rptr.3d 288, 172 P.3d at 744. The Court determined that the rule was content-based because it distinguished favored speech from disfavored speech based on the ideas expressed: speech urging a boycott was prohibited, but other speech was not. Id. at 751-52.
Fashion Valley distinguished the boycott rule from rules prohibiting face-to-face solicitation of funds, which have been held to be content-neutral. The Court explained that solicitation bans are concerned with the manner of speech, and are directed at “the conduct and intrusiveness that face-to-face solicitation for immediate donation or exchange of funds inherently promotes.” Id. at 752-53. Fashion Valley expressly rejected the mail’s argument that the ban on speech advocating a boycott could be similarly justified as a restriction on the manner of speech. Id. at 750, 753 (rejecting the mail’s argument that the boycott ban was “a ‘reasonable regulation’ designed to assure that free expression activities ‘do not interfere with normal business operations’ ... ”). Unlike solicitation, the Court noted, peacefully urging a boycott does not by its nature cause congestion or promote fraud or duress. Id. at 753.
As the California Supreme Court noted, shopping centers are free to “prohibit conduct ‘calculated to disrupt normal business operations’ or that would result in ‘obstruction of or undue interference with normal business operations.’ ” Id. (quoting Diamond, 91 Cal.Rptr. 501, 477 P.2d at 733) (emphasis ours). However, “speech that does no more than attempt to peacefully persuade customers not to patronize a business cannot be banned on the ground that it interferes with normal business operations.” Id. at 751 n. 8. Fashion Valley explained that the “distinction between urging customers to boycott a business and physically impeding access to that business” is crucial. Id. The California Supreme Court also noted that citizens have a “strengthened interest, not a diminished interest, in speech that presents a grievance against a particular business in a privately owned shopping center, including speech that advocates a boycott.” Id. at 750.
The commercial purpose rule at issue here, which was put in place to limit speakers’ abilities to persuade customers not to patronize certain businesses, is an attempt to restrict the speakers’ ability to persuade. The rule does not prohibit conduct that would interfere with normal business operations, but instead infringes upon the strong free speech interest in peacefully presenting a grievance to an offending business. Because limiting critical speech is an impermissible regulatory goal, Rule 2 cannot survive a strict scrutiny analysis.
C
The NLRB correctly held that Rule 4 (application requirement), when used to enforce the unlawful Rules 1 (identification ban) and 2 (commercial purpose rule) is likewise unlawful. The Board reasoned that because the application process is used to screen written material for compliance with the rule banning the identification of a mall owner, manager or tenant, and with the rule banning signage that interferes with the commercial purpose of the Malls, the rule is content-based. We agree, and reiterate that the examination of the content of a speaker’s message is the hallmark of a content-based rule. The *967application requirement becomes unlawful when used as a tool to ferret out objectionable content.
Our conclusion is consistent with that of the California Court of Appeal in H-CHH, in which the Court struck down as constitutionally defective an application process used to screen for expressive activity that would adversely affect the shopping center environment, atmosphere, or image. 193 Cal.App.3d at 1211, 238 Cal.Rptr. 841.6
Macerich argues that even if Rules 1 and 2 are unlawful, the Board’s order is overbroad because it invalidated the application process entirely, even when used to further legitimate goalslike proper scheduling of events. This argument misstates the Board’s order. The ' order enjoins Macerich from “[maintaining and enforcing a rule that requires the presubmission of written materials for the purpose of enforcing” the unlawful identification and commercial purpose rules (emphasis ours). We construe this statement to mean that the application process may remain in use insofar as it is used to promote legitimate time, place, and manner restrictions on expressive activities. So construed, there is nothing overbroad about the holding.
D
We turn to the Unions’ challenge to Rule 3, the ban on carrying or wearing signs. The NLRB concluded that Rule 3 was a reasonable restriction on the time, place, or manner of speech. To be enforceable, restrictions on time, place, or manner must (1) be justified without reference to the content of the regulated speech, (2) be narrowly tailored to serve a significant interest, and (3) leave open ample alternative channels for the communication of the information. Berger v. City of Seattle, 512 F.3d 582, 589 (9th Cir.2008) (citing Clark v. Cmty. for Creative Non-Violence, 468 U.S. 288, 293, 104 S.Ct. 3065, 82 L.Ed.2d 221 (1984)).7 Failure to satisfy any single prong of this test invalidates a regulation. Kuba, 387 F.3d at 858 (quoting Grossman v. City of Portland, 33 F.3d 1200, 1205 (9th Cir.1994)).
The Unions concede that Rule 3 is content-neutral, but argue that it is not narrowly tailored to promote a significant mall interest and does not leave open ample alternatives for communication. To prove that a regulation is narrowly tailored to serve a significant interest, the regulating authority must identify the interests served by the restriction and provide evidence that the proposed communicative activity endangers those interests. Id. at 858-59. Speculation as to what might happen if the proposed activity was allowed is insufficient. Id. at 859-60 (finding lack of evidence to support ban on demonstrating where city failed to provide evidence beyond a “first hand” account that “there is simply no, space in the fire lanes or the concrete apron in which [demonstrators] would be safe ... ”). Studies, anecdotes pertaining to different locales, history, consensus, and “simple common sense” may serve as evidence that the proposed activity will endanger significant interests.
*968G.K Ltd. Travel v. City of Lake Oswego, 436 F.3d 1064, 1073 (9th Cir.2006). In the case of safety restrictions, for example, the regulating body need not wait until someone is injured before promulgating regulations. Edwards v. City of Coeur d’Alene, 262 F.3d 856, 865 n. 16 (9th Cir.2001).
Macerich argues that Rule 3 (signage ban) is justified by convenience, safety, and aesthetic concerns. Valentine testified that the signage ban is necessary to prevent people from having to walk out of their way to avoid expressive activities, keep signage looking professional, and protect individuals from injuries caused by signs or the sticks they are attached to. We generally consider safety and convenience to be valid regulatory objectives. Berger, 512 F.3d at 592. In at least some circumstances, we have recognized aesthetics to be a significant interest. See Foti v. City of Menlo Park, 146 F.3d 629, 637 (noting that while cities do have a substantial interest in protecting the aesthetic appearance of their communities by avoiding visual clutter, these interests may not be compelling). Common sense supports the idea that picketers’ signs may inconvenience retailers and customers by blocking sight lines in shopping centers, although the record does not include evidence to reinforce this conclusion. Similarly, common sense suggests that rigid signs with sharp corners, especially if attached to sharp or heavy sticks, could pose a threat to safety.
While there may be sufficient common sense support for Macerich’s assertion that the proposed communicative activity endangers significant interests, the signage ban is not narrowly tailored to serve those interests. For a regulation to be narrowly tailored, the stated interest must be served “less effectively absent the regulation,” and the regulation may not “burden substantially more speech than is necessary to further the [regulating authority’s] legitimate interests.” Kuba, 387 F.3d at 861. The regulation need not advance the regulating authority’s interests in the least restrictive or least intrusive way, G.K, 436 F.3d at 1074, but the existence of numerous obvious and less-burdensome alternatives is relevant to the regulation’s “fit,” Edwards, 262 F.3d at 865 (quoting City of Cincinnati v. Discovery Network, Inc., 507 U.S. 410, 418 n. 13, 113 S.Ct. 1505, 123 L.Ed.2d 99 (1993)).
The complete ban on wearing or carrying signs eliminates any safety or aesthetic concern associated with signs or sign poles. For that reason, it may be said that Macerich’s interests would be served less effectively absent the ban.8 However, Rule 3 burdens substantially more speech than is necessary to further Macerieh’s legitimate interests. Rule 3 doesn’t just ban speech that is communicated in dangerous or intrusive ways; it bans virtually all speech communicated visually through images and text.9 Moreover, numerous obvious and less burdensome alternatives exist. The same safety considerations *969could be served by eliminating signs with particularly dangerous characteristics. Macerich could, for example, insist that signs be made from soft materials, have rounded corners, or be attached to cardboard poles. Aesthetic and convenience concerns could be promoted by restricting the size of signs or allowing demonstrators to wear signs in the form of lettering on t-shirts. Because the complete ban on carrying or wearing signs is substantially overbroad, it cannot satisfy the requirement that the restriction be “narrowly tailored.”
Even if we held the signage ban to be narrowly tailored to serve a significant interest, it would fail intermediate scrutiny because it fails to leave open ample alternatives for communication.10 See Kuba, 387 F.3d at 858. A regulation that effectively prevents a speaker from reaching his intended audience fails to leave open ample alternatives. Edwards, 262 F.3d at 866. Where “there is no other effective and economical way for an individual to communicate his or her message,” alternative methods of communication are insufficient. Id. We will not invalidate a regulation merely because it restricts the speaker’s preferred method of communication. Id.; see also Savage v. Trammell Crow Co., 223 Cal.App.3d 1562, 1575, 273 Cal.Rptr. 302 (1990) (“The adequacy of alternative channels is not measured by the fondest hopes of those who wish to disseminate ideas.”). However, a regulation that forecloses an entire medium of public expression across the landscape of a particular community or setting fails to leave open ample alternatives. G.K., 436 F.3d at 1074. As we noted in Foti, free speech protections extend to the “right to choose a particular means or avenue of speech ... in lieu of other avenues.” 146 F.3d at 641.
We are particularly wary of any regulation that completely forecloses “a venerable means of communication that is both unique and important.” Gilleo, 512 U.S. at 55, 114 S.Ct. 2038. Picketing is one such venerable medium and has unique advantages over other forms of communication, including immediate recognition by passers-by. Fot% 146 F.3d at 641. In Edwards, we invalidated an ordinance banning the attachment of wooden or plastic supports to signs carried during parades and assemblies because “the classic image of a picketer — dating back to the early days of labor protests — is of an individual holding aloft a sign-bearing standard.” 262 F.3d at 865.
Moreover, when picketing is the chosen means of communication, the location of the protest is particularly important. As the California Supreme Court reiterated in Fashion Valley: “When the activity to be protected is the right to picket an employer, the location of the employer’s business is often the only effective locus; alternative locations do not call attention to the problem which is the subject of the picketing and may fail to apply the desired economic pressure.” 69 Cal.Rptr.3d 288, 172 P.3d at 748 (citing Diamond, 477 P.2d at 733).
Here, the NLRB found that the signage ban left open ample alternatives for communication because the Unions were still *970able to advertise their dispute in the media and picket and handbill on public property. The Board now argues that the mall regulations allow the Unions to attach two signs to a table, thus granting them the advantage of immediate recognition by passers-by. We conclude that these alternatives are legally inadequate. While attaching two signs to a table might allow the Unions to communicate with passersby, such a communication method fails to convey the same message of protest associated with “an individual holding aloft a signbearing standard.” Picketing and handbilling on public property, while preserving the symbolism of the hand-held sign, would fail to reach the Unions’ intended audience: patrons of the Malls or of particular stores within the Malls. Physically removing the protest from the offending employer’s location would seriously diminish the symbolic and economic impact of the message. Advertising the dispute in the media would similarly fail to target the desired audience, and is significantly more expensive. The signage ban left the Unions with a narrow range of ineffective options. Because the signage ban is not narrowly tailored and does not leave open ample alternatives for communication, the Board incorrectly applied the law in determining that Rule 3 was a reasonable time, place, or manner restriction.
E
The Board also found that Rule 5, excluding exterior sidewalks from the designated areas where expressive conduct may occur, was a lawful time, place, or manner restriction.11 Because the Unions concede that this rule is content-neutral, we begin by examining whether it is narrowly tailored to serve a significant interest.12
According to Valentine, limiting expressive activities to certain designated areas is necessary to preserve traffic flow and ensure compliance with fire codes. Mace-rich excluded sidewalks from the designated areas for expressive activities because of a concern that mall patrons would have to step into the street to avoid expressive *971activity on sidewalks, thereby jeopardizing their safety. The Unions acknowledge that these safety and convenience interests are significant, but argue that the exclusion of sidewalks from the designated areas for expressive activity is not narrowly tailored to advance these interests.
Specifically, the Unions argue that the mall sidewalks are no different from — or narrower than — sidewalks in most downtown areas, on which expressive activities are permitted. This reasoning finds support in Grace, in which the United States Supreme Court stated, “the building’s perimeter sidewalks are indistinguishable from other public sidewalks in the city that are normally open to the conduct that is at issue here....” 461 U.S. at 182, 103 S.Ct. 1702. The California Supreme Court has acknowledged that “[pjersons can be excluded entirely from areas where their presence would threaten personal danger or block the flow of passenger or carrier traffic, such as doorways and loading areas.” In re Hoffman, 67 Cal.2d 845, 64 Cal.Rptr. 97, 434 P.2d 353, 358 (Cal.1967). However, Rule 5 restricts significantly more than activity in doorways and loading areas.
The Unions argue that numerous obvious and less restrictive alternatives could achieve the Malls’ goals. For instance, they suggest that fire code compliance could be ensured by regulations prohibiting expressive activities in entrances and other locations that must be kept clear. Cf. Berger, 512 F.3d at 603 (upholding rule restricting expressive activity to sixteen designated locations because the rule furthered “significant city interests, by keeping street performances from posing threats to the flow and convenience of ... patrons in heavily congested areas and entrances to buildings”). We agree, and add that regulations prohibiting the restriction of traffic flow on sidewalks would sufficiently address the other safety and convenience concerns.13
Rule 5 also fails to leave open ample alternatives for communication. We have previously recognized that effective communication depends on the speaker’s ability to address the intended audience. In United States v. Baugh, for example, we held that a statute requiring a permit to demonstrate on National Park property was unlawful when applied so as to refuse a group permission to demonstrate in front of a Park’s visitors’ center. 187 F.3d 1037, 1044 (9th Cir.1999). We noted that the demonstrators were ordered to a “First Amendment area” 150 to 175 yards away from the visitors’ center where their target audience was located, and that this was an insufficient alternative for communication because the demonstrators were “left with no alternative that allowed [them] to reach [their] intended audience.” Id.
*972Here, the Malls cover large areas and have numerous entrances. By banning expressive activity on sidewalks and confining expressive activity to designated areas which may be hundreds of yards from any given store or its patrons, Macerich has effectively cut off access to the Unions’ intended audience(s). The fact that the Unions may still advertise their dispute in the media, and picket and handbill on public property, again fails to cure the constitutional infirmity. Because Rule 5 is not narrowly tailored and does not leave open ample alternatives for communication, it is not a lawful time, place, or manner restriction.
F
Finally, we turn to Rule 6, the prohibition on expressive activities during peak traffic periods. As applied by both Malls, Rule 6 prohibits expressive activity throughout almost the entire holiday shopping period: the time from Thanksgiving through the end of December. During this period, mall traffic doubles, and the Malls’ tenants do 75% of their yearly business. Based on this evidence of increased mall traffic, the Board found the peak traffic rule to be justified by interests in public safety, preserving traffic flow, and controlling congestion.
A complete ban on expressive activities is narrowly tailored only where “each activity within the proscription’s scope is an appropriately targeted evil.” Frisby, 487 U.S. at 485, 108 S.Ct. 2495. Macerich has failed to explain how banning every expressive activity during peak times advances a significant interest. Instead, Macerich attempted to justify the entire ban as a “common sense” measure to decrease crowding during peak times. Numerous less restrictive alternatives would promote the same interest, including a limit on the number of individuals engaged in expressive activities at any one time.14 Although a regulation need not be the least restrictive method of advancing a compelling interest, G.K., 436 F.3d at 1074, the complete ban at issue here is certainly overbroad.
The complete ban on expressive activities, more than any of the other mall rules, fails to leave open ample alternatives for communication. Again, Macerich suggests the alternatives of media advertising, demonstrations on public property, and expressive activity in the Malls during the days of the year when such activity is not entirely prohibited. As discussed above, the options of media advertising and picketing on public property are neither effective nor economical. Limiting expressive activity to non-peak times eliminates the *973opportunity to comment upon or criticize— directly and in-person — tenants’ actions during the time that they make 75% of their sales, and forecloses any chance of effectively reaching a large percentage of the target audience. For these reasons, the peak traffic rule is not a reasonable time, place, or manner restriction.
Ill
Rules 1 (identification ban) and 2 (commercial purpose rule) are impermissible content-based restrictions on expressive activity. Rule 4 (application requirement) is likewise unlawful when used to enforce Rules 1 and 2. Rules 3 (signage ban), 5 (designated areas rule), and 6 (peak traffic rule) are content-neutral, but cannot be justified as reasonable restrictions on the time, place, or manner of expressive activities. Because the promulgation and enforcement of each of these rules impermissibly infringes on the free speech rights preserved by the California Constitution, we hold that the Malls had no right to exclude union representatives from their premises under state law. The enforcement of the contested mall rules against Union representatives, and the exclusion of the Union representatives from mall property, was therefore a violation of section 8(a)(1). We grant the Unions’ petition, grant in part and deny in part the Board’s petition, and deny Macerich’s petition.
PETITIONS GRANTED IN PART; DENIED IN PART
. The challenged regulations are a small portion of the complete "Rules for Public Use of Common Areas,” and are not numbered consecutively in those documents. We adopt the numbering used in the National Labor Relations Board ("NLRB” or "the Board”) opinion.
. Macerich contends that Glendale represents a misapplication of California law, and that the Board erred in relying on it. Even if we were not bound to follow Glendale, see General Const. Co. v. Castro, 401 F.3d 963, 975 (9th Cir.2005) C‘[w]e are bound by decisions of prior panels unless an en banc decision, Supreme Court decision or subsequent legislation undermines those decisions”) (quoting *964Benny v. U.S. Parole Comm'n, 295 F.3d 977, 983 (9th Cir.2002)), we would reject this argument.
First, Macerich argues that Glendale relied on NLRB v. Calkins, 187 F.3d 1080 (9th Cir.1999), and that Calkins has been discredited. While it is true that the cases identifying First Amendment free speech protections on private property relied on by Calkins have been overruled at the federal level, California cases like Pruneyard have incorporated their principles into California law. See Fashion Valley, 69 Cal.Rptr.3d 288, 172 P.3d at 748-49; Pruneyard, 153 Cal.Rptr. 854, 592 P.2d at 346. In addition, Calkins addressed free speech rights on the private property of standalone stores, which have not taken on the functional equivalence of a traditional public forum that was found to be the compelling reason for extending free speech rights in shopping malls in Pruneyard. See 153 Cal.Rptr. 854, 592 P.2d at 347 n. 5. Glendale, which discusses the free speech protections in shopping malls under California law, is good law despite the weaknesses in Calkins.
Macerich next argues that recent decisions of the California Court of Appeal limit Prune-yard's application of free speech rights on private property. Specifically, Macerich points to H-CHH Associates v. Citizens for Representative Gov’t, in which the California Court of Appeal upheld a shopping center’s proscription on the solicitation of funds from patrons and stated that solicitation need not be permitted "when it is basically incompatible with the normal character and function of the facility.” 193 Cal.App.3d 1193, 1221, 238 Cal.Rptr. 841 (Ct.App.1987). Fashion Valley, which reaffirmed Pruneyard, silences this argument. 69 Cal.Rptr.3d 288, 172 P.3d at 748-49. The Fashion Valley court explicitly rejected H-CHH to the extent that it suggested that speech may be prohibited if it competes with a shopping center's merchants. Id. at 753 n. 12.
. California state courts borrow from federal First Amendment jurisprudence to analyze whether a rule is content-based or content-neutral. Glendale, 347 F.3d at 1155.
. In Glendale, we also found the rule to be content-based because it allowed exceptions for commercial literature naming a mall owner, manager, or tenant, and for literature from groups and persons who were in a primary labor dispute with a mall tenant. These additional details enhance the content-based nature of the regulation, but were not necessary to a finding that the regulation was content-based.
. California state courts also draw from First Amendment jurisprudence to determine whether a content-based rule survives strict scrutiny under the California Constitution. Glendale, 347 F.3d at 1156.
. Macerich argues that our analysis should be guided instead by Union of Needletrades, Industrial & Textile Employees, AFL-CIO v. Superior Court, 56 Cal.App.4th 996, 65 Cal.Rptr.2d 838 (Ct.App.1997) ("UNITE”), in which the California Court of Appeal upheld an application process for. expressive activity in a shopping mall. UNITE gives no guidance because the Court did not address whether the underlying restrictions on naming tenants and on interfering with the commercial purposes of the mall were valid, as it found that those issues had not been properly preserved for review. Id. at 1020-21.
. California Courts apply federal precedent to determine whether a rule is a reasonable time, place, or manner restriction. See Kuba v. 1-A Agric. Ass’n, 387 F.3d 850 (9th Cir.2004).
. The dissent would have us stop here, before analyzing whether the regulation burdens substantially more speech than is necessary to further Macerich’s legitimate goals or determining whether numerous obvious and less-burdensome alternatives exist. The volume of speech burdened and the availability of numerous alternatives are appropriate considerations in a complete and thorough narrow tailoring analysis. We are not, as the dissent suggests, insisting that the challenged regulation be the “least restrictive means” for achieving Macerich’s goals. We agree that such an analysis would be inappropriate where, as here, intermediate scrutiny is the appropriate standard. See, e.g., Ward, 491 U.S. at 797, 109 S.Ct. 2746.
. There are exceptions, of course. The Unions could have distributed handbills or attached two signs to a table within an area designated for expressive conduct.
. The dissent essentially asks us to ignore this prong of the analysis, stating that "the Supreme Court has repeatedly admonished lower courts not to use the 'ample alternative channels’ requirement as a means of overturning regulations.” The cases cited by the dissent, however, stand for the proposition that this Court may not overturn a valid time, place, or manner restriction on the grounds that we disagree with the regulating authority’s methods. See, e.g., Ward, 491 U.S. at 799, 109 S.Ct. 2746. These cases do not suggest that the "ample alternative means” requirement is no longer a valid prong of the time, place, and manner analysis.
. Federal courts have consistently protected expressive activities on public sidewalks. See, e.g., United States v. Grace, 461 U.S. 171, 103 S.Ct. 1702, 75 L.Ed.2d 736 (1983) (invalidating statute prohibiting distribution of leaflets and display of signs on sidewalks on Supreme Court grounds because not narrowly tailored). California courts have extended the same protection to privately-owned sidewalks surrounding privately-owned shopping malls. See In re Lane, 71 Cal.2d 872, 79 Cal.Rptr. 729, 457 P.2d 561 (1969) (reaffirmed in Fashion Valley, 172 P.3d at 747).
. The dissent avoids this analysis by claiming that the validity of a regulation restricting petitioning activities to two designated areas has already been determined by the California courts. The dissent cites the California Court of Appeals's decision in UNITE, 56 Cal.App.4th at 1012, 65 Cal.Rptr.2d 838. The dissent then claims that a "state appellate court's determination of state law is binding and must be given deference,” citing Hicks v. Feiock, 485 U.S. 624, 629-30, 630 n. 3, 108 S.Ct. 1423, 99 L.Ed.2d 721 (1988) for support. Hicks actually says that a federal court is not to apply a rule different from that stated by the state intermediate appellate court where "the highest court has refused to review the lower court’s decision rendered in one phase of the very litigation which is now prosecuted by the same parties before the federal court.” Id. at 630 n. 3, 108 S.Ct. 1423. This is not the case here, Hicks also states that "where an intermediate appellate state court rests its considered judgment upon the rule of law which it announces, that is a datum for ascertaining state law which is not to be disregarded by a federal court unless it is convinced by other persuasive data that the highest court of the state would decide otherwise.” Id. A thorough time, place, and manner analysis convinces us that the California Supreme Court would conclude that the exclusion of sidewalks from the designated areas for expressive activities violates free speech protections.
. Macerich argues that UNITE, 56 Cal.App.4th at 1010-13, 65 Cal.Rptr.2d 838, compels a contrary conclusion. We note that the rule discussed by the California Court of Appeal in UNITE prohibited a demonstration in front of a particular store because the demonstration would have violated a fire code. The UNITE court held that the preferred demonstration area was not an appropriate place to conduct expressive activities. Id. at 1012. In the situation at issue here, no fire code was shown to have been violated; there is no demonstrated reason that sidewalks are not an appropriate place for expressive activities.
While the reasoning in UNITE was extrapolated to apply to several other mall rules, including rules that are more similar to Rule 5, the UNITE court did not perform a narrow tailoring analysis on any restriction other than that prohibiting a demonstration that would have violated a fire code. Because the analysis of whether a restriction on expressive activity is sufficiently narrowly tailored is necessarily a fact-specific inquiry, see Berger, 512 F.3d at 601-04 (analyzing whether several restrictions on the location of speech activities sufficiently matched the stated interests), UNITE does not guide our analysis here.
. The Board points to H-CHH and UNITE, in which California courts upheld similar restrictions on expressive activities during peak traffic periods, to support its conclusion that the peak traffic rule is permissible. Because neither H-CHH nor UNITE explicitly addressed whether the regulations in question were narrowly tailored, we do not find them informative in this analysis. The dissent also cites Costco Cos., Inc. v. Don Gallant, 96 Cal.App.4th 740, 753, 117 Cal.Rptr.2d 344 (Ct.App.2002). The context in Costco was markedly different from that in the present case. Costco supplied evidence that petition gatherers in its store had directly interfered in the store’s business, and imposed considerable expenses, administrative burdens, and risks. Id. at 750-51, 117 Cal.Rptr.2d 344. Petition gatherers had physically and verbally abused staff and customers, and altercations between proponents and opponents of particular petition gathering efforts had escalated to the point that rifles had been pointed at petition gatherers. Id. at 751-52, 117 Cal.Rptr.2d 344. Given these circumstances, the court determined that Costco had the right to impose regulations designed to protect its business operations, and that limiting interferences to its less profitable days was a rational restriction. Id. at 753, 117 Cal.Rptr.2d 344.