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
Canning Dam did occur in the early stages of construction. In March 1934 there was a violent storm bringing of rain in less than two days. As a result, the river rose rapidly which flooded the dam foundation workings. Pumps had to be installed and work resumed three days later. The dam was completed in September 1940. When built it was the longest concrete gravity dam in Australia, and also the second highest after the Burrinjuck Dam in New South Wales. As of 1997 of the 90 large concrete and masonry gravity dams in Australia the Canning Dam is still the fifth