Beginning during the later years of the Great Depression and continuing during and after World War II, a series of government reports prepared during the Roosevelt, Truman and Eisenhower administrations led to the National Interstate and Defense Highways Act of 1956 that authorized the construction of a 41,000 mile system of limited-access and grade separated highways that now span the nation.

The key reports created and published between 1939, and 1955, include:

U.S. Bureau of Public Roads (1939). Toll Roads and Free Roads. This document is also available here. 

Interregional Highways Committee (1944). A Report of the National Interregional Highway Committee. This document is also available here.

Federal Works Agency (1949). Highway Needs of the National Defense. This document is also available here.

Commissioner of Public Roads (1954). Needs of the Highway Systems, 1955-84. This document is also available here.

Advisory Committee on a National Highway Program (1955). National Highway Program. This document is also available here.