Interstate 65 (I-65) is part of the Interstate Highway System that runs 887.30 miles (1,427.97 km) north–south from Mobile, Alabama, to Gary, Indiana. The highway crosses Kentucky from south to north, from the Tennessee state line near Franklin to the Indiana state line in Louisville. I-65 passes through three of Kentucky's ten largest cities—Bowling Green, Elizabethtown, and Louisville—and serves Mammoth Cave National Park and Fort Knox. Kentucky was the first state to complete its portion of I-65, with the final section, located near Franklin, opening in 1970.