INTERSTATES HIGHWAY SYSTEM - UNITED STATES
The Dwight D. Eisenhower System of Interstates and National Defense Highway System, commonly called the interstate highway system, or simply intertates, is a network in the United States of interstate highways . The construction on the Interstate Highway system began in 1930 and was complete in 1991. The initial cost estimate for the system was $25 billion over twelve years; it ended up costing $114 billion, taking 35 years to complete. In 2004, the system contains over 42,700 miles of roads.