Boulder Canyon (Colorado River) steamboats as they passed over the dangerous rapids of Devil's Gate Canyon, during their high water runs to the mouth of the Virgin River at Rioville, Nevada. Boulder Canyon (Colorado River) Boulder Canyon, originally Devils Gate Canyon, is a canyon on the Colorado River, above Hoover Dam, now flooded by Lake Mead. It lies between Clark County, Nevada and Mohave County, Arizona. It heads at western end of the Virgin River Basin of Lake Mead, at about . Boulder Canyon divides the Black Mountains into the Black Mountains of Arizona, and the Black Mountains of Nevada. Its mouth is now
Steamboats of the Colorado River Quartette Landing and Eldorado Canyon in Nevada, the landings and the mills there were abandoned. The town of Nelson was founded near the head of the canyon nearest the road to the railroad, the post office of Eldorado was closed in August 31, 1907 and moved to Nelson. In 1906, Santa Fé railroad built the Barnwell and Searchlight Railway to the west to tie Searchlight to its subsidiary California Eastern Railway at Barnwell, California. Also in 1905, the Arizona and California Railroad bridged the Colorado River at Parker, Arizona, cutting in half the last profitable section of the river for