Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in 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 least populous U.S. state, with a U.S. Census population of 563,626 in 2010. This is a 14.1% increase since 2000. It is the tenth largest U.S. state by area. Cheyenne is the capital and the most populous city of Wyoming with a population of nearly 60,000 people within its city proper.