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Interstate 15 (I-15) is an Interstate Highway, running from San Diego, California, United States, to the Canadian border, through Mohave County in northwest Arizona. Despite being isolated from the rest of Arizona, in the remote Arizona Strip, and short in length at , it remains notable for its scenic passage through the Virgin River Gorge. The highway heads in a northeasterly direction from the Nevada border northeast of Mesquite, Nevada, to the Utah border southwest of St. George, Utah. The south portion of I-15's route was built close to the alignment of the old U.S. Route 91 (US 91), but the northern section, through the Virgin River Gorge, was built along roadless terrain. The southern section of the highway was complete and open in the early 1960s, but the gorge section was inaccessible until 1973. When it opened, the Virgin River Gorge passage was the most expensive section of rural Interstate per mile. == Route description == The highway is signed and designated the ''Veterans Memorial Highway'', a designation which continues into Utah. Traffic volume along the Arizona section of I-15 is approximately 23,000 vehicles per day. The highway is also a part of the CANAMEX Corridor, a trade corridor in North America linking Edmonton, Alberta in Canada and Mexico City. The highway enters the state in Mohave County northeast of Mesquite and Las Vegas, Nevada, paralleling the old US 91 heading northeast on an alignment north of the Virgin River. I-15 parallels the Virgin River for its entire length in Arizona, but the terrain abruptly becomes more rugged at mile 13, where the Virgin River Gorge begins. The first interchange is exit 8 at Littlefield, where old US 91 turns north to avoid the gorge. I-15 crosses the river for the first time just beyond Littlefield, and soon passes another interchange serving local roads eastwards. This exit, exit 9, is a right-in/right-out design with frontage roads, constructed after the initial opening. Access under I-15 is provided just south of the ramps.〔 Beyond exit 9, I-15 enters the Virgin River Gorge, first passing through "The Narrows". Here, the gorge features limestone cliffs that are as high as above the highway. Several pulloffs allow access to these cliffs. Within the canyon, through which it ascends northbound and descends southbound, five bridges cross the river. The highway generally follows the winding course of the river, but several rock cuts bypass bends.〔 The canyon opens up slightly at the Cedar Pocket interchange (exit 18), allowing for a rest area. This rest area was turned over to the federal Bureau of Land Management in 2002 which maintains the nearby Virgin River Gorge Recreation Area. The rest area was demolished in 2009. I-15 continues to parallel the Virgin River, but begins to deviate more.〔 Trees here include tamarix, ash, cottonwoods, willows and Joshua trees. Wildflowers such as globemallow, marigold, and sand verbena dot the route in springtime.〔 At mile 22.5, the highway crosses the Virgin River for the final time, continuing east along the smaller Black Rock Gulch before then turning slightly northeast into a flatter area. The final interchange (exit 27) provides local access. A weigh station/port of entry formerly served both sides of the road near mile 28 before the Utah state line.〔 The weigh station/port of entry are now combined into a joint Arizona/Utah facility just north of the state line staffed by the Arizona Department of Transportation (DOT) Motor Vehicle Division and Utah DOT Motor Carrier Division. I-15 continues on into Utah providing access to St. George as well as Salt Lake City.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Interstate 15 in Arizona」の詳細全文を読む スポンサード リンク
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