The Federal Highway Administration classifies roads according to the type of service provided and the type of area (rural or urban) using the Highway Functional Classification System (HFCS) (see figure below). There are three major types of roads: arterial, collector, and local.
Arterials provide the highest level of mobility for long, uninterrupted travel. Arterials are designed to a higher standard than other roads, have multiple lanes, and limited access. The Interstate Highway System is part of the arterial network. Rural arterials provide interstate and intercounty service. Rural principal arterials, in general, connect areas with populations of 25,000 or more. The urban principal arterial network serves large urban centers and high traffic corridors. Urban principal arterials also provide continuity with rural arterials and serve most trips entering and leaving urban areas. Urban minor arterials connect with urban principal arterials and rural connectors and are designed for medium length trips and moderate mobility.
Collectors provide shorter distance access between and within residential and business areas at lower speeds than arterials. These roads collect and distribute traffic from the arterial network and connect with local roads. Most collectors are two lanes.
Local roads pick up traffic from collectors and provide direct access to residences and businesses.
U.S. Department of Transportation, Federal Highway Administration, Federal Transit Administration, 1999 Status of the Nation's Highways, Bridges, and Transit: Conditions and Performance (Washington, DC: 2000).
U.S. Department of Transportation, Federal Highway Administration, Our Nation's Highways: Selected Facts and Figures 1998 (Washington, DC: 1998).