For the purpose of this part:

Sign means an outdoor sign, light, display, device, figure, painting, drawing, message, placard, poster, billboard, or other thing which is designed, intended, or used to advertise or inform, any part of the advertising or informative contents of which is visible from any place on the main traveled way of the Interstate or Federal-aid primary highway.

Main traveled way means the through traffic lanes of the highway, exclusive of frontage roads, auxiliary lanes, and ramps.

Interstate System means the National System of Interstate and Defence Highways described in section 103(d) of title 23 U.S.C.

Primary system means the Federal-aid highway system described in section 103(b) of title 23 U.S.C.

Erect means to construct, build, raise, assemble, place, affix, attach, create, paint, draw, or in any other way bring into being or establish.

Maintain means to allow to exist.

Scenic area means any area of particular scenic beauty or historical significance as determined by the Federal, State, or local officials having jurisdiction thereof, and includes interests in land which have been acquired for the restoration, preservation, and enhancement of scenic beauty.

Parkland means any publicly owned land which is designated or used as a public park, recreation area, wildlife or waterfowl refuge or historic site.

Federal or State law means a Federal or State constitutional provision or statute, or an ordinance, rule, or regulation enacted or adopted by a State or Federal agency or a political subdivision of a State pursuant to a Federal or State constitution or statute.

Visible means capable of being seen (whether or not legible) without visual aid by a person of normal visual acuity.

Freeway means a divided arterial highway for through traffic with full control of access.

Rest area means an area or site established and maintained within or adjacent to the highway right-of-way by or under public supervision or control for the convenience of the traveling public.

Directional and official signs and notices includes only official signs and notices, public utility signs, service club and religious notices, public service signs, and directional signs.

Official signs and notices means signs and notices erected and maintained by public officers or public agencies within their territorial or zoning jurisdiction and pursuant to and in accordance with direction or authorization contained in Federal, State, or local law for the purposes of carrying out an official duty or responsibility. Historical markers authorized by State law and erected by State or local government agencies or nonprofit historical societies may be considered official signs.

Public utility signs means warning signs, informational signs, notices, or markers which are customarily erected and maintained by publicly or privately owned public utilities, as essential to their operations.

Service club and religious notices means signs and notices, whose erection is authorized by law, relating to meetings of nonprofit service clubs or charitable associations, or religious services, which signs do not exceed 8 square feet in area.

Public service signs means signs located on school bus stop shelters, which signs:

Identify the donor, sponsor, or contributor of said shelters;

Contain public service messages, which shall occupy not less than 50 percent of the area of the sign;

Contain no other message;

Are located on schoolbus shelters which are authorized or approved by city, county, or State law, regulation, or ordinance, and at places approved by the city, county, or State agency controlling the highway involved; and

May not exceed 32 square feet in area. Not more than one sign on each shelter shall face in any one direction.

Directional signs means signs containing directional information about public places owned or operated by Federal, State, or local governments or their agencies; publicly or privately owned natural phenomena, historic, cultural, scientific, educational, and religious sites; and areas of natural scenic beauty or naturally suited for outdoor recreation, deemed to be in the interest of the traveling public.

State means any one of the 50 States, the District of Columbia, or Puerto Rico.

Urban area means an urbanized area or, in the case of an urbanized area encompassing more than one State, that part of the urbanized areas in each such State, or an urban place as designated by the Bureau of the Census having a population of five thousand or more and not within any urbanized area, within boundaries to be fixed by responsible State and local officials in cooperation with each other, subject to approval by the Secretary. Such boundaries shall, as a minimum, encompass the entire urban place designated by the Bureau of the Census.