The construction of the interstate highway system and regional parkways during the late 1950s through the early 1970s initially reduced the use and need of the belt routes. As urbanization of the county spread further out from the City of Pittsburgh, however, the Belt System helped to reduce the effects of suburban congestion. Many of the roads selected over fifty years ago today play key roles in the long-range regional transportation plans of Allegheny County. Many of the roads chosen for the belts have been converted from simple country lanes to urban collector roads and to urban arterials.