Federal and state laws propel billboard code enforcement.
Colorado is one of 23 “bonus” states participating in a federal program that rigorously controls outdoor advertising along all interstate highways. The program originated with the Federal-Aid Highway Act of 1958 and gives participating states 0.5% over and above their allocation for construction. The act allows several types of signs within federal interstate property:Directional and officialOn-premise for sale, lease, or activityWithin 12 air miles of advertised activityIn the public interest, e.g., historic sights, lodging, eating, and vehicle repair.
The Highway Beautification Act of 1965 — championed by former first lady Lady Bird Johnson to enhance recreational travel, safety, and natural beauty — established federal control of billboards within 660 feet of interstates in bonus states. This act contains no pre-1956 right-of-way exemption (i.e., legislation preceding the Federal-Aid Highway Act of 1958), mandating instead that commercial billboards be allowed only in commercial/industrial and unzoned areas.
For the most part, the act and subsequent amendments maintain the types of allowable signs under the 1958 legislation, while establishing four categories of signs, each with its own requirements regarding size, lighting, and spacing limitations. States that don't effectively control outdoor advertising adjacent to their roads risk a 10% reduction in annual federal highway fund allocations.
The 1965 act remains the overarching federal legislation for control of billboards near roadways; later legislation, such as the 1978 Surface Transportation Assistance Act, has largely dealt with funding and federal/state jurisdictional issues such as how often messages on electronic billboards can change.
Like other states, Colorado adds its own laws to the federal framework to control outdoor advertising near state roads; for example, signs may not advertise illegal activities.