Federal Highway Administration, America's Highways 1776–1976: A History of the Federal-Aid Program (1977)
“ As the street and highway networks expanded, more and more people found it convenient to live in the suburbs and drive to and from work, but the convenience decreased rapidly as the highways became congested with ever-increasing volumes of vehicles. The city, county and State highway authorities tried to keep up with the traffic increase, first by widening streets and highways and then by providing special high-capacity roads such as parkways and expressways, commonly financed by bond issues. ”
