A Policy on Geometric Design of Highways and Streets (Green Book), American Association of State Highway and Transportation Officials, Washington, D.C., (2004)

A Policy on Design Standards—Interstate System, American Association of State Highway and Transportation Officials, Washington, D.C., July 1991).

Wikipedia Article: 7/9/13

Standards for Interstate Highways in the United States are defined by the American Association of State Highway and Transportation Officials (AASHTO) in the publication A Policy on Design Standards - Interstate System. For a certain highway to be considered an Interstate, it must meet these construction requirements or obtain a waiver from the Federal Highway Administration.