The Dwight D. Eisenhower National System of Interstate and Defense Highways, which has been called the most ambitious public works project built since the Roman Empire, is the most critical link in New Hampshire’s transportation system.
- New Hampshire has 235 miles of Interstate routes running the length of the state and connecting the state’s major urban areas.
- New Hampshire's Interstate system, which includes three percent of all roadway lane miles in the state, carries 23 percent of all vehicle travel in the state.
- Since funding of the Interstate system was approved in 1956, vehicle miles of travel in New Hampshire have increased by 419 percent, the state’s population has increased by 125 percent from approximately 580,000 to 1.3 million and the number of vehicles in New Hampshire has increased by 429 percent.
