Allegheny County belt system

The Allegheny County Belt System color codes various county roads to form a unique system of routes in Allegheny County, Pennsylvania, and around the city of Pittsburgh.

Unlike many major American cities with belt systems composed of number-coded limited-access roads, the Allegheny County Belt System roads are not intended to be used as high-speed routes. Rather, the system is a navigational aid for motorists in unfamiliar portions of the county. Five routes were introduced in the early 1950s: from outermost to innermost, the Red, Orange, Yellow, Green, and Blue Belts. The Purple Belt was added later. All roads in the system retain their original names.