The Interstate Highway System was launched when President Dwight D. Eisenhower signed the Federal-Aid Highway Act of 1956. Its purpose was to provide high-speed, high-capacity system of highways without stoplights and with exits spaced, whenever possible, at least a mile apart.
Planning for what is now known as the Dwight D. Eisenhower National System of Interstate and Defense Highways or just "The Interstate System," began in the late 1930`s. The Federal-Aid Highway Act of 1938 called on the Bureau of Public Roads (BPR) to study the feasibility of a toll-financed system of three east-west and three north-south superhighways. The report that resulted showed that a toll network would not be self-supporting. Instead, it advocated a 26,700-mile interregional highway network.
In 1941, President Franklin D. Roosevelt appointed a National Interregional Highway Committee, headed by Commissioner of Public Roads Thomas H. MacDonald, to evaluate the need for a national expressway system. The committee`s January 1944 report, Interregional Highways, supported a system of 33,900 miles, plus an additional 5,000 miles of auxiliary urban routes.
Examples of design standards for the Interstate System include full control of access, design speeds of 50 to 70 miles per hour (depending on type of terrain), a minimum of two travel lanes in each direction, 12-foot lane widths, 10-foot right paved shoulder, and 4-foot left paved shoulder. Initially, the design had to be adequate to meet the traffic volumes expected in 1975. Later, the requirement was changed to a more general 20-year design period to allow for evolution of the System.
More than 42,000 miles of the Interstate System have been, almost entirely at the expense of the federal government, which has spent more than one hundred billion dollars.