sweetwater county

Coal production at the Union Pacific mines at Reliance, Wyo., north of Rock Springs peaked at 1.4 million tons per year in the early 1940s. The mines are closed now but a vast steel-and-concrete tipple remains. Visitors are welcome, with a caveat: Stay out of the interior.

Green River, Wyo., on its namesake river and on the Union Pacific Railroad, began as a stage station. After the U.P. relocated switching and roundhouse operations there in the early 1870s, the Green River rail yard became one of the busiest in the nation. Since the early 1900s, this county seat of Sweetwater County has weathered many booms and busts of nearby oil, gas and trona development, with the railroad and county government steadying its economy all the while.