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
Steamboats of the Colorado River to make only two trips with forty tons in that time. Trips farther up river to the vicinity of Fort Mohave took at least twice as long. The same difficulty plagued the "Colorado" carrying cargo between the estuary and Arizona City. By the fall of 1863 there was a backlog of twelve hundred tons of freight at Arizona City or in ships anchored in the estuary waiting to be brought up river. Between ten and fifty tons of ore waiting to be brought down to the estuary at each of the landings up river above Arizona City. Some of this