Virgin River Gorge

For most of its length Arizona is bounded by the Colorado River, but its far northwest corner — the Arizona Strip, the slice of state stranded north of the Grand Canyon and reachable only by first leaving Arizona — was defined by a smaller stream. The Virgin River, draining the high plateaus of southern Utah, sawed through the Beaver Dam Mountains and left a gorge that drops an average of seventy feet per mile, ten times the grade of the Colorado through the Grand Canyon. Its walls climb more than a thousand feet, banded in limestone and sandstone laid down across 500 million years, at the seam where the Colorado Plateau breaks down into the Mojave Desert.

This is Nuwuvi country — the Southern Paiute, who followed the river's thin water and mesquite through a land short on both. For centuries the gorge was a barrier rather than a road; by every early account, passage through it on foot or horseback was close to impossible.

Then federal highway planners looked at the same canyon and decided Interstate 15 would run straight down it, to save twelve miles and win gentler grades for trucks. The result, opened to traffic on December 14, 1973 after nearly a decade of blasting, was the most expensive rural interstate ever built per mile in the United States — a distinction it held until Boston's Big Dig. Crews rechanneled the Virgin River twelve times and carried the road across it on seven bridges in twenty-nine miles. The stretch barely touches Arizona and serves it almost not at all; it links Utah to Nevada, and Utah quietly advanced its own federal road funds to Arizona to see it finished.

Today it is one of the genuine drives of the interstate system — four lanes threading a red-and-gray canyon so deep and narrow the winter sun never reaches the floor in places. There is a BLM campground and rest area at Cedar Pockets, and the sheer walls have made the gorge a noted destination for hard sport climbing. It is worth slowing for. This is the only piece of Arizona you reach by leaving it.