Wyoming is a state in the Western United States. The western two-thirds of the state is covered mostly with the mountain ranges and rangelands of the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High Plains. Wyoming is the 10th largest U.S. state by area, and it is the least populous, with a U.S. Census population of 563,626 in 2010. This is a 14.1 percent increase since 2000. Cheyenne is the capital and the most populous city of Wyoming.