The Worley Highway District brought suit against Kootenai County, challenging the validity of an ordinance enacted by the county commissioners in 1980. The issue is whether the Local Planning Act of 1975, I.C. §§ 67-6501, et seq., gives a county the authority to set standards for street naming and address numbering within the boundaries of a local highway district. In a summary judgment proceeding, the district court upheld the validity of such a county ordinance. We affirm.
In April of 1980, the Kootenai County Commissioners enacted County Ordinance No. 43, entitled “Kootenai County Street Naming and Numbering Ordinance.” The purpose of the ordinance was to establish a standardized system of street naming and numbering throughout the county. To accomplish this goal, the ordinance promulgated a series of standards to govern selection of street names and assignment of address numbers within the county’s unincorporated areas. Upon passage of the ordinance, the highway district, a political subdivision located entirely within Kootenai County, filed this suit seeking declaratory relief. The highway district contends that the county ordinance is void because the Idaho Code gives the highway district the exclusive authority to administer local highways.
In granting summary judgment, the district court concluded that the Local Planning Act of 1975 authorized the county commissioners to adopt standards for street naming and numbering. Moreover, the court determined that in adopting the Local Planning Act the legislature intended that special purpose districts, such as the highway district, comply with any ordinances enacted by the county commissioners pursuant to the Act.
The highway district contends that by virtue of I.C. §§ 40-1611 and 1615, it has the exclusive power to administer county roads within its boundaries. Idaho Code § 40-1611 states in part:
*835The highway commissioners ... shall have ... exclusive general supervision and jurisdiction over all highways within their district, with full power to construct, maintain, repair and improve all highways within the district ... and ... shall have, in addition to the powers and duties conferred by this chapter, in respect to the highways within such district, all of the powers and duties that would by law be vested in the county commissioners of the county and in the district road overseers if such highway district had not been organized....
Idaho Code § 40-1615 provides in addition:
The grant of powers in this chapter contained' to highway districts and highway boards and the officers and agents thereof, shall be liberally construed, as a broad and general grant of powers, to the end that the control and administration of such districts may be efficient; nor shall the enumeration of certain powers that would be implied without such enumeration be construed as a denial or exclusion of other implied powers necessary for the free and efficient exercise of the powers expressly granted.
The trial court concluded — and we agree — that a conflict exists between these statutes and the following provisions of the Local Planning Act on which the county relies. Idaho Code § 67-6504 states: “A city council or board of cóunty commissioners, hereafter referred to as a governing board, may exercise all of the powers required and authorized by this chapter in accordance with this chapter.” Idaho Code § 67-6518 specifies that “each governing board may adopt standards for such things as ... roadways, streets, lanes, bicycle-ways, pedestrian walkways . .. street numbers and names; house numbers, schools, hospitals, and other public and private development.” Finally I.C. § 67-6528 states in part: “The State of Idaho and all its agencies, boards, departments, institutions, and local special purpose districts, shall comply with all plans and ordinances adopted under this chapter unless otherwise provided by law.... ”
It is a cardinal principle of statutory construction that where possible to do so courts must harmonize and reconcile statutes which apparently conflict. Sampson v. Layton, 86 Idaho 453, 457, 387 P.2d 883, 885 (1963).
Principles of statutory interpretation require this Court to ascertain and give effect to the legislative intent. Summers v. Dooley, 94 Idaho 87, 481 P.2d 318 (1971); Jorstad v. City of Lewiston, 93 Idaho 122, 456 P.2d 766 (1969). “The intent of the legislature may be implied from the language used, or inferred on grounds of policy or reasonableness.” Summers v. Dooley, supra [94 Idaho] at 89, 481 P.2d at 320.
Gavica v. Hanson, 101 Idaho 58, 60, 608 P.2d 861, 863 (1980).
It is clear to us that I.C. §■ 40-1611, together with I.C. § 40-1615, gives highway commissioners broad powers to administer highways within their districts. Their domain includes not only the “exclusive general supervision and jurisdiction over all highways,” but also “full power to construct, maintain, repair, and improve all highways within the district.” This language makes the legislature’s intent clear that in the area of construction, maintenance, and day-to-day operation of highways, the prerogative of the highway commissioners is exclusive.
On the other hand, in enacting the Local Planning Act of 1975, the legislature obviously intended to give local governing boards, such as the Kootenai County Commissioners, broad powers in the area of planning and zoning. Commensurate with their planning responsibilities, county commissioners, pursuant to I.C. § 67-6518, may establish standards for a wide variety of projects and activities, including street numbers and names.
The Local Planning Act of 1975 imposes upon cities, and counties in unincorporated areas, the duty to promote rational development of local land and resources. To be effective and meaningful, planned development must encompass a broad range of activities, resources, and facilities. The leg*836islature has recognized this and has invested the powers and responsibilities for such sweeping functions in cities and counties— deeming those entities of local government best equipped and experienced to deal broadly with the problems. The legislature has chosen not to fragment those responsibilities among various other local units of government which have, for the most part, limited and specialized functions.
The purposes of the Local Planning Act, and the duties of those charged with its administration, are closely related to the planning and zoning functions that have long been the domain of cities and counties. Of necessity these functions transcend the boundaries of local special purpose districts, such as highway districts. For example, § 67-6511 of the Act provides that, in carrying out an adopted plan, the governing board of each city and county may establish one or more zoning districts, and, where appropriate, establish standards to regulate and restrict the size, construction, location, and use of buildings and structures. The statute requires that “all standards shall be uniform for each class or kind of buildings throughout each [zoning] district.... ” These provisions support the view that it was the intent of the legislature for standard setting functions to be vested with cities and counties, rather than with local special purpose districts. Nothing in the Act itself suggests a legislative intent for the planning and standard setting authority of the county under the Act, in respect to highways, to “flow to” highway districts by reason of the language of I.C. § 40-1611.
Other sections of our code also lend more support to the position taken by the county than to the position of the highway district. For example, § 40-501 “Duties of county commissioners" was amended in 1943 to add the following duty, to be performed by “proper ordinances:”
12. To rename any street or highway within the county, excepting those situated within the territorial limits of incorporated cities, towns and villages when such renaming will eradicate confusion and be in the public interest.
This section is significant because it does not exclude highway or road districts from its operation. The amendment — enacted after the quoted provisions of § 40-1611 were enacted — indicates that the legislature, even before the Local Planning Act of 1975, believed it was a legitimate function of county commissioners to have overriding authority to name streets when necessary to “eradicate confusion.”
In determining legislative intent of a statute it is appropriate to consider other statutes dealing with the same or with related subjects. Local 1494 of the International Association of Firefighters v. City of Coeur d’Alene, 99 Idaho 630, 639, 586 P.2d 1346, 1355 (1978). Title 50, Chapter 13 of the Idaho Code governs the filing of subdivision plats. All such plats, before filing, must be presented to the appropriate governing body of a city and/or county for approval. I.C. §§ 50-1301 through 1329, 67-6513. Each plat must show all streets and have all streets named. I.C. § 50-1304. A plat cannot be accepted for filing until it has been submitted, approved, and accepted by the appropriate governing body. Inferentially, this includes the right to approve or disapprove street names and designations. The legislature clearly intended this function to be the exclusive domain of the cities and counties. It is consistent with this legislative intent to have the counties and cities set standards for naming and numbering of streets.
Finally, we consider the following provisions from the Local Planning Act of 1975:
67-6528. Applicability of ordinances.— The state of Idaho, and all its agencies, boards, departments, institutions, and local special purpose districts, shall comply with all plans and ordinances adopted under this chapter unless otherwise provided by law. In adoption and implementation of the plan and ordinances, the governing board or commission shall take into account the plans and needs of the state of Idaho and all agencies, boards, departments, institutions, and local special purpose districts. The provisions of plans and ordinances enacted pursuant to *837this chapter shall not apply to transportation systems of statewide importance as may be determined by the Idaho transportation board. The Idaho transportation board shall consult with the local agencies affected specifically on site plans and design of transportation systems within local jurisdictions. [Emphasis added.]
The Worley Highway District is one of the “local special purpose districts” mentioned in I.C. § 67-6528, which the legislature has said “shall comply with all plans and ordinances adopted under this chapter unless otherwise provided by law.” The section goes on to exclude “transportation systems of statewide importance as may be determined by the Idaho Transportation Board.” If the legislature intended also to exclude highway districts from the operation of this section, it is reasonable to assume it would have explicitly done so.
Our Supreme Court has stated on numerous occasions that “when two governmental promulgations are in irreconcilable conflict, the one enacted later in time governs.” Mickelsen v. City of Rexburg, 101 Idaho 305, 307, 612 P.2d 542, 544 (1980). The principle is applicable here. The language in § 40-1611 upon which the highway district relies — quoted earlier in this opinion— was first enacted in 1911. The language has not subsequently been materially changed although the section has been amended.1 The later enacted, more specific provisions of the Local Planning Act of 1975 ought to be the more persuasive statement of legislative intent. Even § 40-501, as amended in 1943 to give the county commissioners the authority to rename streets and highways in unincorporated areas when necessary to eradicate confusion, is a later expression of legislative intent. The same can be said of those sections of the Idaho Code which we have mentioned, governing the approval of subdivision plats by cities and counties.
For these reasons we conclude the district court was correct in ruling that the Local Planning Act of 1975 authorized the county commissioners to adopt, by ordinance, county-wide standards for street naming and numbering in all unincorporated areas of the county. Accordingly, we affirm the summary judgment order of the district court. Costs to respondents.
WALTERS, C.J., concurs.. Section 40 1611 was last amended effective July 1, 1982, to specifically grant the board of highway commissioners of each highway district the power to “establish and post speed and other regulatory signs.” 1982 Sess.Laws, ch. 304. This amendment was enacted after the briefs were filed in this appeal and its effect was not discussed by counsel during oral argument. However, we do not perceive that this amendment affects the county commissioners’ authority to set standards for naming and numbering streets.