High Quality Content by WIKIPEDIA articles! Interstate 15 is the fourth-longest north south transcontinental Interstate Highway in the United States, traveling through the states of California, Nevada, Arizona, Utah, Idaho, and Montana. The Idaho, Utah and Arizona portions have been officially designated the 'Veterans Memorial Highway'. Since I-15's inception, it has served as a long-haul route for North American commerce. It is now officially chartered for this purpose. From the junction of Interstate 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.