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