Deseret

geographical name

Des·​er·​et ˌde-zə-ˈret 

proposed state of the U.S. south of the 42nd parallel and west of the Rockies that was organized in 1849 by a convention of Mormons but was refused recognition by the U.S. Congress

Note: Deseret would have included most of present-day Utah, much of Nevada, and parts of Idaho, Wyoming, Colorado, New Mexico, Arizona, and southern California.