 interstate 15 (i-15) is the eleventh longest interstate highway, following interstate 20, and it is the fourth longest northâsouth interstate highway in the united states. i-15 passes through the states of montana, idaho, utah, arizona, nevada, and california, and from the canadian border to san diego county, close to the mexican border. this interstate highway serves the major cities of butte, montana, salt lake city, las vegas, and san diego. it also passes close to the urban areas of helena, montana, ogden, utah, los angeles county, california, and orange county, california. the stretches of interstate 15 in idaho, utah, and arizona have been designated as the "veterans memorial highway". since the creation of interstate 15, 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. local portions were built to connect the inland empire with san diego in california, facilitate tourism access to las vegas, interconnect all of the metropolitan statistical areas in utah except for logan, and provide freeway bypasses for [[pocatello, idaho|poca
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