Course of the Colorado River into the Virgin River, which ran southward through what is now Overton Arm to join the Colorado River near the now-ghost town of St. Thomas, Nevada. At Hoover Dam, the Colorado turns due south through Black Canyon, a direction it will follow for the remainder of its course to the Gulf of California. It passes under the Mike O'Callaghan–Pat Tillman Memorial Bridge (Hoover Dam Bypass), the highest concrete arch bridge in the world, carrying U.S. Route 93 at a height of above the Colorado River. At the end of Black Canyon the Colorado widens into Lake Mohave, created by the
Course of the Colorado River load. The area around the confluence is dominated geographically by Navajo Mountain which rises over a mile (1.6 km) above the surrounding landscape, which is part of the Navajo Nation. Rainbow Bridge, one of the highest natural bridges in the world, is located at the tip of an arm of Lake Powell at the foot of Navajo Mountain. Glen Canyon Dam, which creates Lake Powell, is situated in the town of Page in northern Arizona only about by river from the Utah border. The dam impounds the Colorado primarily for hydroelectricity generation. In front of the dam the Glen Canyon