National Defense Highway System
When President Eisenhower went to Kansas to announce the interstate highway system, he announced it as "the National Defense Highway System." In 1956 President Eisenhower signed legislation establishing the National System of Interstate and Defense Highways (about 41,000 miles of roads). Since then, DOD has continued to identify and update defense-important highway routes. The National Defense Highway system was designed to move military equipment and personnel efficiently

By the late 1930s, the pressure for construction of transcontinental superhighways was building. It even reached the White House, where President Franklin D. Roosevelt repeatedly expressed interest in construction of a network of toll superhighways as a way of providing more jobs for people out of work. He thought three east-west and three north south routes would be sufficient. Congress, too, decided to explore the concept. The Federal-Aid Highway Act of 1938 directed the chief of the Bureau of Public Roads (BPR) to study the feasibility of a six route toll network. Some observers thought the plan lacked the vision evident in the popular "Futurama" exhibit at the 1939 New York World's Fair. The exhibit's designer, Norman Bel Geddes, imagined the road network of 1960 - 14-lane superhighways crisscrossing the nation, with vehicles moving at speeds as high as 160 km per hour. The Federal-Aid Highway Act of 1944 authorized designation of a 65,000-km "National System of Interstate Highways," to be selected by joint action of the state highway departments. Construction of the interstate system moved slowly.

In 1919, Lt. Colonel Dwight D. Eisenhower accompanied the Army's first transcontinental motor convoy from Washington, DC, to San Francisco, thereby forming an image in the future President's mind of a system of cross continental highways that eventually led to the concept of the National Defense Highway System. During World War II, Gen. Eisenhower saw the advantages Germany enjoyed because of the autobahn network. He also noted the enhanced mobility of the Allies when they fought their way into Germany. President Eisenhower established the Highway Trust Fund to create a funding mechanism that enabled the United States to build a national road network similar to the German Autobahn.

From the outset of construction of the Interstate System, the DOD has monitored its progress closely, ensuring direct military input to all phases of construction. The National Defense Highway System was responsible for building many of the first freeways. Its purpose was supposedly to allow for mass evacuation of cities in the event of a nuclear attack. The Interstate system was designed so that one mile in every five must be straight, usable as airstrips in times of war or other emergencies.

In February 1994, the American Society of Civil Engineers (ASCE) designated the Dwight D. Eisenhower System of Interstate and Defense Highways as one of the "Seven Wonders of the United States." (Other "wonders" include the Golden Gate Bridge, Hoover Dam, and the Panama Canal.) As ASCE noted, the interstate system has often been called "the greatest public works project in history." It not only linked the nation, but it boosted productivity and helped sustain a more than tenfold increase in the gross national product since the start of the program in 1956. It is the backbone of the world's strongest economy. However, the story of the interstate system is really the story of its individual segments, many of which were engineering wonders in themselves.

When the system specifications for the then National Defense Highway System were being devised, public transportation policy makers determined at-grade intersections, both with railways and other roadways, were simply incompatible with the intended operational characteristics of such a facility, and they were excluded in any and all forms. While this decision had significant engineering and economic consequences and resulted in numerous local dislocations when it came to designing and putting the system in place, in retrospect it should be obvious any other decision would have had profoundly adverse effects on the mobility, capacity, safety and efficiency of the Interstate system as it exists today. Access only by interchanges with ramps and acceleration / deceleration lanes allow vehicles to enter and leave the highway with minimal effect on the through traffic stream. Interstate highways do not have direct driveway access to adjacent properties, grade level intersections, transit stops, pedestrian facilities or railroad grade crossings, all of which interfere with the rapid and free flow of traffic.

The Dwight D. Eisenhower National System of Interstate and Defense Highways consists of limited access facilities of the highest importance to the nation and are built to uniform geometric standards. They connect, as directly as practicable, the principal metropolitan areas, cities and industrial centers and provide important routes to, through and around urban areas. They serve national defense purposes and connect at border points with Canada and Mexico along routes of continental importance.