Some Little-Known Facts About America's Interstate Highway System

Published June 30, 2016 at 11:33 AM CDT

Vehicles travel along Interstate 70 near Odessa, Missouri (Charlie Riedel/AP)

Interstate highways in the United States stretch more than 47,000 miles, with more planned in coming years. At 60 years old, it is not hard to argue the impact of the Federal Highway Act of 1956, which propelled the Interstate Highway System into existence.

In the second of a two-part look at America’s highways, Here & Now‘s Jeremy Hobson offers some little-known facts and figures about the system.

Hear part one of our look at America’s interstate highway system

10 Interstate Highway Facts

The Interstate Highway System stretches 47,622 miles and includes 10 transcontinental routes varying from 18 miles to 3,000 miles.
Longest: I-90, 3,085.3 miles (Seattle to Boston)
Shortest: I-97, 17.6 miles (Annapolis to Baltimore, Maryland)
State with the most Interstate mileage: Texas, 3,232.04 miles
State with the most Interstate routes: New York, 29 routes
Interstate routes across the most states: 1-95, 16 states (Florida to Maine)
Heaviest traveled Interstate: I-405, 374,000 vehicles per day
Annual spending on the Interstate Highway System is estimated to be $20.2 billion
Highest: 11,158 feet (I-70, Eisenhower Tunnel in the Colorado Rocky Mountains)
Lowest: −103 feet (I-95, Fort McHenry Tunnel under the Baltimore Inner Harbor)