National Highway System
Today, the interstate highway system traverses 46,747 miles of urban, suburban and rural country in every state except Alaska. As of the system’s 50th anniversary in 1996, it accounted for nearly a quarter of all United States road traffic despite accounting for only 1.1 percent of the nation’s total road surface, and nearly one trillion person-miles (a person-mile is one mile traveled for each person inside a vehicle) driven, on roadways that undergo constant analysis in the best interest of defense, commerce, and public use. While the National Interstate and Defense Highway System has become a vital public resource and a key plot point in the American story, it remains a focus of the Department of Defense’s Strategic Highway Network, a 140,000 mile-wide web of government-designated highways and roads connecting military installations, economic hubs, railroads, and ports.
The Leonard P. Zakim Bunker Hill Memorial Bridge, opened on 30 March 2003, carries eight lanes of Interstate 93 over the Charles River in Boston, Massachusetts.