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 29.43 miles (47.36 km), 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.

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 500 feet (150 m) 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.

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