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 most difficult rapids. At Hite the Hite Crossing Bridge – the only bridge over the Colorado for nearly – carries Utah State Route 95 over the river. Below here the Colorado is joined by the Dirty Devil River and begins to widen into Lake Powell, the giant reservoir formed by Glen Canyon Dam downstream. Lake Powell, a popular houseboating destination, is surrounded by the Glen Canyon National Recreation Area and receives over 2 million visitors each year despite its remote location. Before the dam was completed in 1966 the Colorado flowed through Glen Canyon, a sandstone gorge known for its