The State of Wyoming ( ) is a state in the northwestern region of the United States. The majority of the state is dominated by the mountain ranges and rangelands of the Rocky Mountain West, while the easternmost section of the state includes part of a high altitude prairie region known as the High Plains. While the tenth largest U.S. state by size, Wyoming is the least populous, with a U.S. Census estimated population of 522,830 in 2007, a 5.9% increase since 2000. The capital and the most populous city of Wyoming is Cheyenne.

Location and size

As specified in the designating legislation for the territory of Wyoming, the state is defined as a geoellipsoidal rectangle bounded by lines of latitude and longitude. Wyoming is one of only three states (along with Colorado and Utah) to have only latitudinal and longitudinal, rather than naturally-defined, boundaries. In reality, due to survey errors during the 19th century, Wyoming's border deviates from the latitude or longitude lines by up to half of a mile (.8 km) in some spots, especially in the mountainous region along the 45th parallel. Wyoming is bordered on the north by Montana, on the east by South Dakota and Nebraska, on the south by Colorado, on the southwest by Utah, and on the west by Idaho. It is the tenth largest state in the United States in total area, containing 97,818 square miles (253,348 km²) and is made up of 23 counties. From the north border to the south border it is 276 miles (444 km); and from the east to the west border is 365 miles (587 km) at its south end and 342 miles (550 km) at the north end.

Mountain ranges

The Great Plains meet the Rocky Mountains in Wyoming. The state is a great plateau broken by a number of mountain ranges. Surface elevations range from the summit of Gannett Peak in the Wind River Mountain Range, at 13,804 feet (4,207 m), to the Belle Fourche River valley in the state's northeast corner, at 3,125 feet (952 m). In the northwest are the Absaroka, Owl Creek, Gros Ventre, Wind River and the Teton ranges. In the north central are the Big Horn Mountains; in the northeast, the Black Hills; and in the southern region the Laramie, Snowy and Sierra Madre ranges.

The Snowy Range in the south central part of the state is an extension of the Colorado Rockies in both geology and appearance. The Wind River Range in the west central part of the state is remote and includes more than 40 mountain peaks in excess of tall in addition to Gannett Peak, the highest peak in the state. The Big Horn Mountains in the north central portion are somewhat isolated from the bulk of the Rocky Mountains.

The Continental Divide spans north-south across the central portion of the state. Rivers east of the divide drain into the Missouri River Basin and eventually the Gulf of Mexico. They are the North Platte, Wind, Big Horn and the Yellowstone rivers. The Snake River in northwest Wyoming eventually drains into the Columbia River and the Pacific Ocean, as does the Green River through the Colorado River Basin.