Defendants appeal the district court’s decision to grant summary judgment to plaintiff Wendy Faustin on her claim under 42 U.S.C. § 1983 that her First Amendment rights were violated. We affirm in part, reverse in part, and remand.
I.
On several occasions, Faustin displayed a banner at the Perry Street overpass in Denver. The banner measures three feet by ten feet and reads “Abortion kills children.” Faustin and a friend stand on the sidewalk of the overpass to display the banner, each holding one end of the banner. Motorists in cars traveling on Highway Six, the roadway running under the overpass, can see the banner. The overpass consists of a road with a sidewalk running along one side. The sidewalk is public property, intended for pedestrian traffic. The sidewalk is approximately five feet wide, and a fence runs along it to prevent pedestrians from falling onto the highway below the overpass.
On December 5, 1997, Faustin was displaying the banner at the overpass when Denver Police Officer Lindsay approached her and asked her to stop displaying the banner. Faustin complied but asked Lindsay to cite the specific law she was violating. Sergeant Subia of the Denver Police arrived a short time later. The two officers reviewed a traffic manual but could find no law proscribing the display of the banner. The officers told Faustin they were unaware of any law she had violated by displaying the banner. On February 6, 1998, Faustin was displaying the banner at the overpass when Sergeant Reyes of the Denver Police informed her she could not display the banner. Faustin told Reyes she was finished for the day, and Reyes did not pursue the matter.
On March 6, 1998, Faustin was displaying the banner at the overpass when Denver Police Officer Blea told her she was violating the Posting Ordinance (Denver *946Municipal Code section 3 l).1 Blea consulted with Lieutenant Fink, who noted Faustin’s banner also violated the Outdoor Advertising Act. See Colo.Rev.Stat. § 43-1-401 et seq (1999). Following Faustin’s March 6 encounter with the Denver Police, her attorney sent a letter to then-Police Chief Michaud requesting assurances that Faustin would not be arrested for displaying the banner, but received no response.
On August 7, 1998, Faustin was displaying the banner at the overpass when she was approached by Denver Police Officer Awe. Within fifteen minutes, four other police cars arrived. Sergeant Honer cited Faustin for violating section 3-1. The charge was formally dismissed on October 9. The City Prosecutor determined that the posting ordinance did not apply because the banner was not affixed to anything. Faustin’s attorney wrote to Police Chief Sanchez requesting assurance that Faustin would not be arrested for displaying the banner, but received no response.
On November 18, 1998, Assistant City Attorney Thomas sent a memorandum to Chief Sanchez advising him that Faustin’s conduct was protected speech activity which could continue until and unless an actual public safety hazard was presented. Thomas also advised Chief Sanchez that any regulation of speech on the overpass required a compelling'state interest and needed to be narrowly tailored.
Faustin filed her 42 U.S.C. § 1983 complaint on November 23, 1998. The complaint alleged that Denver’s policy of prohibiting speech on the overpass, specifically application of section 3-1 to Faustin’s display of the banner, was unconstitutional. As regards an alleged unlawful policy, custom or practice, Faustin alleged in her complaint that “Defendant City and County of Denver police officers have, on at least four (4) separate occasions, approached Plaintiff and unlawfully demanded that she remove the handheld display of the sign from the Perry Street overpass. These repeated unlawful demands constitute a policy, custom, or practice of the Denver Police Department.” ApltApp. at 21. The complaint goes on to allege that “[a]s a direct and proximate result of Defendants’ actions, and the customs, practices, and policies of the Denver Police Department, Plaintiff is chilled and deprived of her right to free speech [and free exercise of religion and free assembly]. Plaintiff has suffered, is suffering, and will continue to suffer irreparable harm as a direct result of Defendants’ conduct.” Id. at 23. Faus-tin requested declaratory and injunctive relief, as well as nominal damages, costs, and fees. Defendants moved to dismiss the complaint pursuant to Federal Rule of Civil Procedure 12(b)(1), claiming the case was moot and that Faustin lacked standing because the charge against her had been dismissed and was unlikely to recur. The district court denied the motion.
The parties filed cross-motions for summary judgment. Defendants argued that Faustin properly could have been charged with violating Colorado Revised Statute section 42^1-606(1).2 Faustin responded *947that section 42-4-606(1) was vague and overbroad. In granting summary judgment in favor of Faustin, the district court held that section 3-1 was unconstitutional as applied to Faustin and that section 42-4-606 was facially unconstitutional because it was vague and overbroad as interpreted by defendants. See Faustin v. City & County of Denver, 104 F.Supp.2d 1280 (D.Colo.2000).
II.
On appeal, defendants contend (1) Faus-tin lacks standing to challenge defendants’ application of section 3-1 to her conduct because she seeks prospective relief for injuries that may not occur; (2) Faustin’s constitutional challenge of section 3-1 as regards the section’s application to her conduct is moot because the charge against Faustin was dismissed before this action was filed; (3) Faustin lacks standing to challenge the constitutionality of section 42-4-606 because she was never charged with violating that statute; (4) the district court erred in declaring section 42-4-606 facially unconstitutional; (5) the district court erred in holding the overpass walkway is a traditional public forum; and (6) the district court erred in finding municipal liability because there was no evidence to support a finding of a policy, practice, or custom of charging Faustin or others with violating section 3-1 when engaging in protected speech activities.
We review the grant of summary judgment de novo, applying the same legal standard as the district court. Mesa v. White, 197 F.3d 1041, 1043 (10th Cir.1999). Summary judgment is proper if the evidence, viewed in the light most favorable to the non-movant, shows there is no genuine issue of material fact and that the moving party is entitled to judgment as a matter of law. Smith v. City of Enid, 149 F.3d 1151, 1154 (10th Cir.1998).
Standing and mootness
We review questions of standing and mootness de novo. See Colo. Farm Bureau Fed’n v. United States Forest Serv., 220 F.3d 1171, 1173 (10th Cir.2000); F.E.R. v. Valdez, 58 F.3d 1530, 1532-33 (10th Cir.1995). Those who seek to invoke the jurisdiction of the federal courts must satisfy the Article III requirement of having an actual case or controversy. City of Los Angeles v. Lyons, 461 U.S. 95, 101, 103 S.Ct. 1660, 75 L.Ed.2d 675 (1983). “Plaintiffs must demonstrate a personal stake in the outcome in order to assure that concrete adverseness which sharpens the presentation of issues necessary for the proper resolution of constitutional questions.” Id. (internal quotations omitted). Plaintiffs must show they have sustained or are immediately in danger of sustaining some direct injury, and the injury or threat of injury must be real and immediate, not conjectural or hypothetical. Id. at 101-02, 103 S.Ct. 1660. To establish standing, plaintiffs must show injury in fact, a causal relationship between the injury and the challenged action of the defendant, and a likelihood that the injury will be redressed by a favorable decision. Byers v. City of Albuquerque, 150 F.3d 1271, 1274 (10th Cir.1998).
Defendants contend Faustin lacks standing to challenge the application of *948section 3-1 to her conduct because the section 3-1 charge against Faustin was dismissed before this civil case was filed, and she is not being prosecuted under section 3-1 at this time. Defendants are partially correct. Faustin has standing to sue for damages based on her prosecution (including nominal damages, which she sought) and to seek declaratory relief with respect to her prosecution. See F.E.R., 58 F.3d at 1533 (“The Patients’ claim for a declaratory judgment is similar to their claim for damages. In each, the Patients ask the court to determine whether a past constitutional violation occurred. In this dispute the alleged liability-producing act has already occurred. Because the question still exists as to whether the defendants violated the Patients’ right to privacy, a controversy on the Patients’ right to privacy still exists.... Therefore, the claim for a declaration that the defendants improperly invaded the privacy of the Patients when they seized the psychiatrist’s files is not moot and this claim will be discussed later with the claim for damages.”). However, she lacks standing to seek injunctive relief with respect to section 3-1. To have standing, Faustin must show a real and immediate threat that she will be prosecuted under this statute in the future. O’Shea v. Littleton, 414 U.S. 488, 495-96, 94 S.Ct. 669, 38 L.Ed.2d 674 (1974). In light of the city prosecutor’s determination that Faustin was not violating the posting ordinance because she was holding the sign and it was not affixed in any way, it is not likely she will again be charged under section 3-1.
Defendants also contend Faustin lacks standing to challenge the constitutionality of section 42-4-606. Defendants are correct that Faustin cannot challenge section 42-4-606 as being unconstitutional in application. See Phelps v. Hamilton, 122 F.3d 1309, 1327 (10th Cir.1997). The statute was not applied to Faustin and was not mentioned in her complaint.
Faustin argues her challenge of the statute is a facial challenge under the overbreadth doctrine. Facial challenges to statutes are sometimes permissible, especially where speech protected by the First Amendment is at stake. N.Y. State Club Assoc. v. City of N. Y., 487 U.S. 1, 11, 108 S.Ct. 2225, 101 L.Ed.2d 1 (1988). To prevail on a facial attack, the plaintiff must demonstrate that the challenged law either could never be applied in a valid manner or, “even though it may be validly applied to the plaintiff and others, it nevertheless is so broad that it may inhibit the constitutionally protected speech of third parties.” Id. (internal quotations omitted). “[T]here must be a realistic danger that the statute itself will significantly compromise recognized First Amendment protections of parties not before the Court for it to be facially challenged on overbreadth grounds.” Members of City Council of Los Angeles v. Taxpayers for Vincent, 466 U.S. 789, 801, 104 S.Ct. 2118, 80 L.Ed.2d 772 (1984).
Faustin offers no explanation of how the statute inhibits the speech of third parties. Rather, she argues that the statute unconstitutionally inhibits her own speech and that if she were prosecuted under it, the statute would be unconstitutionally applied to her. The overbreadth doctrine does not apply where there is no significant difference between the claim that the ordinance is invalid because of overbreadth and the claim that it is unconstitutional when applied to the plaintiffs own activities. See id. at 802, 104 S.Ct. 2118 (holding plaintiffs lacked standing under overbreadth doctrine because they “have not attempted to demonstrate that the ordinance applies to any conduct more likely to be protected by the First Amendment than their own crosswires signs”). *949The overbreadth doctrine is inapplicable to Faustin’s claim and does not provide standing for her to challenge the constitutionality of section 42-4-606.
Traditional Public Forum
The First Amendment does not guarantee access to property simply because it is owned or controlled by the government. See Perry Educ. Ass’n v. Perry Local Educators’ Ass’n, 460 U.S. 37, 46, 103 S.Ct. 948, 74 L.Ed.2d 794 (1983). There are three categories of government property: (1) traditional public fora; (2) designated public fora; and (3) nonpublic fora. Hawkins v. City & County of Denver, 170 F.3d 1281, 1286 (10th Cir.1999).
Faustin argues the overpass is a sidewalk, which is quintessentially a public forum. Streets and parks “have immemorially been held in trust for the use of the public and, time out of mind, have been used for purposes of assembly, communicating thoughts between citizens, and discussing public questions.” Hague v. Comm. for Indus. Org., 307 U.S. 496, 515, 59 S.Ct. 954, 83 L.Ed. 1423 (1939) (Roberts, J., concurring). The Supreme Court has observed that “[n]o particularized inquiry into the precise nature of a specific street is necessary; all public streets are held in the public trust and are properly considered traditional public fora.” Frisby v. Schultz, 487 U.S. 474, 481, 108 S.Ct. 2495, 101 L.Ed.2d 420 (1988). Defendants rely on three cases to draw a distinction between sidewalks and walkways. Defendants contend these three cases are applicable here and render the overpass a nonpublic forum.
In United States v. Kokinda, 497 U.S. 720, 110 S.Ct. 3115, 111 L.Ed.2d 571 (1990), the issue was whether the sidewalk in front of the post office was a traditional public forum. The Court found it lacked the characteristics of a public sidewalk traditionally open to expressive activity. Specifically, it was not a thoroughfare, but a sidewalk constructed “solely to assist public patrons to negotiate the space between the parking lot and the front door of the post office, not to facilitate the daily commerce and life of the neighborhood or city.” Id. at 728, 110 S.Ct. 3115. The Court concluded that “the location and purpose of a publicly owned sidewalk is critical to determining whether such a sidewalk constitutes a public forum.” Id. at 728-29, 110 S.Ct. 3115. Here, the overpass does not lead from a parking lot to the front door of a building, but enables pedestrian traffic to cross over a highway. Relinks the parallel sides of the street to one another, acting as a thoroughfare between them rather than providing access to a single remote location.
In Chicago Acorn v. Metropolitan Pier and Exposition Authority, 150 F.3d 695 (7th Cir.1998), the issue was whether the sidewalks on Navy Pier were traditional public fora. The court concluded that “[r]ather than being part of the city’s automotive, pedestrian, or bicyclists’ transportation grid, the sidewalks on the pier ... are internal to the pier.” Id. at 702. Here, the overpass is not in an isolated segment of town that is set apart from everything.
In Jacobsen v. Bonine, 123 F.3d 1272 (9th Cir.1997), the court determined that the perimeter walkways of interstate rest areas are not traditional public fora. The court held that “[t]hese walkways are integral parts of the rest stop areas, which are themselves oases from motor traffic.” Id. at 1274. Jacobsen is not similar to the present case as the overpass here is directly connected to other sidewalks and is part of general pedestrian traffic. We used a similar line of analysis in Hawkins. We found that the walkways in the Galleria were not public fora because they were not *950“part of Denver’s automotive bicycle or pedestrian transportation grid, for [the Galleria] is closed to vehicles, and pedestrians do not generally use it as a throughway to another destination.” 170 F.3d at 1287. Here, the overpass is part of the transportation grid, and pedestrians use it as a gateway to the other side of the highway.
In a case analogous to the case at bar, Lytle v. Brewer, 77 F.Supp.2d 730 (E.D.Va.1999), a group displayed antiabortion signs on a pedestrian overpass running over a highway. The court, noting that “nothing in the record indicates that the overpass was built for anything other than for what is expected-to aid the general public in crossing over the highway, similar to a sidewalk which protects pedestrians from traffic,” concluded the overpass was a traditional public forum. Id. at 736. Defendants argue the overpass is distinct from a sidewalk because it is suspended in air. However, the fact that the overpass (the roadway and its adjacent sidewalk) is suspended does not disqualify it as a traditional public forum.
Policy, practice, or custom
The district court treated this case as a challenge to section 3-1 and section 42-4-606. However, closer analysis of the complaint, the motions for summary judgment, and the briefing before us indicates that Faustin also challenges defendants’ policy of prohibiting all expression on overpasses. Defendants admit this policy exists. The policy is subject to First Amendment challenge. See Hawkins, 170 F.3d at 1286 (“The First Amendment applies not only to legislative enactments, but also to less formal governmental acts, such as city policies.”).
Faustin has standing to challenge the policy. See Hawkins, 170 F.3d at 1286. She has been asked to remove her banner on four separate occasions. Further, she intends to continue to display her banner at the overpass, which means there is a real and immediate threat that defendants will continue to enforce their policy against her. Faustin has shown injury in fact and has shown a causal relationship between the injury and the challenged action of the defendants. Further, she has shown a likelihood that the injury will be redressed by a favorable decision. The district court should address this issue on remand.
III.
We REVERSE the district court’s holding that Faustin has standing to pursue injunctive relief to prevent future application of section 3-1 to her banner activities, but AFFIRM the district court’s holding that she has standing to pursue declaratory relief and nominal damages regarding defendants’ past enforcement of section 3-1 against Faustin. We REVERSE the district court’s holding that Faustin’s claim was not moot with respect to injunctive relief, but AFFIRM with respect to declaratory relief and nominal damages.
We REVERSE the district court’s holding that Faustin has standing to challenge section 42^1-606 and its holding that 42-4-606 is unconstitutional. We AFFIRM the district court’s holding that the overpass is a traditional public forum. We REMAND to the district court for further proceedings to address whether defendants’ policy violates Faustin’s First Amendment rights.
. Denver Municipal Code art. I, § 3-1 provides in relevant part:
(a) It shall be unlawful to post, paint, or attach ... in any manner any handbill, poster, advertisement or notice of any kind upon public property except by permission of the manager of the public works pursuant to established rules and regulations, or on private property except by permission of the owner or authorized agent of the owner of such property-
. Colo.Rev.Stat. § 42-4-606(1) provides in part:
No person shall place, maintain, or display upon or in view of any highway any unautho*947rized sign, signal, marking, or device which purports to be or is an imitation of or resembles an official traffic control device or railroad sign or signal, or which attempts to direct the movement of traffic, or which hides from view or interferes with the effectiveness of any official traffic control device or any railroad sign or signal, and no person shall place or maintain nor shall any public authority permit upon any highway any traffic sign or signal bearing thereon any commercial advertising.