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
Black Canyon of the Gunnison National Park into Gunnison Gorge National Conservation Area. The canyon's name owes itself to the fact that parts of the gorge only receive 33 minutes of sunlight a day, according to "Images of America: The Black Canyon of the Gunnison". In the book, author Duane Vandenbusche states, "Several canyons of the American West are longer and some are deeper, but none combines the depth, sheerness, narrowness, darkness, and dread of the Black Canyon." The Gunnison River drops an average of through the entire canyon, making it the 5th steepest mountain descent in North America. By comparison, the Colorado River drops an average