| I-5 (I-5) is the main Interstate Highway on the West Coast of the United States, paralleling the Pacific Ocean from Canada to Mexico (Washington to southernmost California, linking one BC to another) and serving some of the largest cities of that part of the U.S., including Seattle, Tacoma, Portland, Sacramento, San Francisco/Oakland, Los Angeles, and San Diego. It links the state capital cities of Washington, Oregon, and California. Its southern terminus is at the United States - Mexico border. Its northern terminus is at the Canada-United States border. Interstate 5 is the only Interstate Highway to touch both the Canadian and Mexican borders. At its southern end, I-5 continues into Tijuana, Mexico, as Mexico Federal Highway 1. On its northern end, I-5 continues into Vancouver, British Columbia, Canada, as British Columbia Highway 99.