 Rock Springs has been shaped by a unique mining history. Did you know that at one time there was many as 10 mines in the downtown area? When the mines opened in the 1880s, immigrants flocked to Rock Springs, making it one of the most ethnically diverse spots in the western U.S. Locals proudly declared the town as the home of 56 nationalities. Rock Springs quickly became one of the nation's leaders in coal production. The Union Pacific Railroad helped to sustain the area's growth by using the high-quality coal to power their steam engines and by selling the coal on the market. Rock Springs has experienced booms and busts. During the depression of the 1890s and the Great Depression in the 1930s, the industry suffered. Another bust occurred in the mid-1950s when Union Pacific locomotives switched to diesel fuel. Fortunately for the local economy, the Jim Bridger and Black Butte coal mines were built in the late 1970s which brought new jobs. After a century of pulling coal from underneath the town, the last mine in Rock Springs proper closed in 1963. The Rock Springs area remains a major contributor to Wyoming's mining industry, with coal mines like Black Butte and Jim Bridger serving as a reminder of the remarkable production of the past.