Interstate 15 (I-15) is a major Interstate Highway in the western United States. I-15 begins near the Mexico–US border in San Diego County and stretches north to Alberta, Canada, passing through the states of California, Nevada, Arizona, Utah, Idaho, and Montana. The interstate serves the cities of San Diego, San Bernardino, Las Vegas, St. George, Provo, Salt Lake City, Ogden, Pocatello, Idaho Falls, Butte, Helena, and Great Falls. It also passes close to the urban areas of Orange County, California and Los Angeles County, California. The stretches of I-15 in Idaho, Utah, and Arizona have been designated as the "Veterans Memorial Highway". The southern end is at a junction with Interstate 8 and State Route 15 (CA 15) in San Diego, and the northern end is at a connection with Alberta Highway 4 at the Sweetgrass–Coutts Border Crossing.
I-15 was built to connect the Inland Empire with San Diego in California, facilitate tourism access to Las Vegas, provide access to the Arizona Strip, interconnect all of the metropolitan statistical areas in Utah except for Logan, and provide freeway bypasses for Pocatello, Idaho Falls, and Great Falls. Since its creation, I-15 has served as a long-haul route for North American commerce. It is now officially chartered for this purpose: from the junction of I-515 in Las Vegas to the Canadian border, I-15 forms part of the CANAMEX Corridor, a High Priority Corridor, as a result of the North American Free Trade Agreement. Also since the construction of I-15, California, Nevada, and Utah have consistently ranked in the fastest-growing areas of the United States. As a result, the route of I-15 has substantially increased in population and commuter traffic.