Interstate 5 (I-5) is the main Interstate Highway on the West Coast of the United States, running largely parallel to the Pacific coast of the continental U.S. and U.S. Route 99 from Mexico to Canada, through the states of California, Oregon and Washington. It serves some of the largest cities on the U.S. West Coast, including Seattle, Portland, Sacramento, Los Angeles, and San Diego, and also links the capital cities of Washington (Olympia), Oregon (Salem), and California (Sacramento) together. The highway's southern terminus is the Mexico–United States border and its northern terminus is the Canada–United States border; it is currently the only continuous Interstate highway to touch the U.S. borders with both Canada and Mexico. Upon crossing the Mexican border at its southern terminus, Interstate 5 continues to Tijuana, Baja California as Mexico Federal Highway 1. Upon crossing the Canadian border at its northern terminus, it continues to Vancouver as British Columbia Highway 99. It is the 12th longest highway in the U.S. following Interstate 15 and the 5th longest north-south highway following Interstate 15.