How Long Did It Take The U.S. To Build The Interstate Highway System?

The U.S. Interstate Highway System took 36 years to complete, stretching from 1956 to 1992. The Federal-Aid Highway Act authorized 41,000 miles of highways with a $25 billion budget. The system was designed for defense and commerce, with final segments completed in Colorado and California. The project faced delays and varied completion dates. It remains the world's longest road network.