The history of St. Thomas, Nevada, the remains of which today lay under the high water mark of Lake Mead, begins in 1865 with Mormon missionaries sent by Brigham Young to the Moapa Valley to grow cotton. In 1871 the boundary of Utah territory was shifted east by one degree longitude, and the town became part of Nevada. New settlers moved in, miners and farmers, interacting with the Mormons and native Paiutes. The building of Hoover Dam doomed the small settlement, yet a striking number of people still have connections to a town that ceased to exist three-quarters of a century ago. Today, the...