"By the mid-1850's, as easy pickings in the California gold country diminished, prospectors began to pull out and spread across the West in hopes of striking it rich elsewhere. Gold was discovered on the Nevada side of the Sierra Nevada, in the Colorado Rockies, and along the Frasier River in British Columbia. New strikes occurred in Montana and Wyoming during the 1860's, a decade later in the Black Hills of South Dakota, and in the Coeur d'Alene region of Idaho during the 1880's" (America, p.492).
During the 19th century, the "Far West" (anything west of the Rocky Mountains) was considered almost inhospitable. Aside from the difficulties associated with crossing the Rockies, most of the area south of Washington and Oregon was considered too dry and mountainous for farming and sustaining life. But in 1848, gold was discovered in Sutter's Mill in California, and sparked the famous Gold Rush. Out of the Gold Rush came settlement of the "Far West." Settlers created "islands" of civilization in an inhospitable land. Cities began to sprout up in the middle of barren areas in California, Colorado, Nevada, and other surrounding areas. As hundreds of thousands of Gold Rushers flooded into California, the Gold resources began to become depleted. In the mid-1850's, prospectors started moving North and East to Montana, Wyoming, Colorado, New Mexico, Arizona, Utah and Idaho. In the 1880's, gold was discovered in the Coeur d'Alene area of Idaho, sparking the usual spike in population from prospectors in search of gold.