Interstate Highway System

The Dwight D. Eisenhower National System of Interstate and Defense Highways, commonly known as the Interstate Highway System, is a network of controlled-access highways that forms part of the National Highway System in the United States.

Construction of the original Interstate Highway System was proclaimed complete in 1992, despite deviations from the original 1956 plan and several stretches that did not fully conform with federal standards.

The cost of construction of the Interstate Highway System was approximately $114 billion (equivalent to $530 billion in 2019).

The system has continued to expand and grow as additional federal funding has provided for new routes to be added, and the system will grow into the future.

As of 2018, about one-quarter of all vehicle miles driven in the country used the Interstate Highway System, which had a total length of 48,741 miles (78,441 km).