a state in the mountain region of the Western United States. Wyoming is the 10th most extensive, but the least populous and the 2nd least densely populated of the 50 U.S. 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. Cheyenne is the capital and the most populous city of Wyoming with a population of nearly 60,000 people within its city proper.

As specified in the designating legislation for the Territory of Wyoming, Wyoming's borders are lines of latitude, 41°N and 45°N, and longitude, 104°3'W and 111°3'W (27° W and 34° W of the Washington Meridian), making the shape of the state a latitude-longitude quadrangle.[5] Wyoming is one of only three states (along with Colorado and Utah) to have borders along only straight latitudinal and longitudinal lines, rather than being defined by natural landmarks. Due to surveying inaccuracies during the 19th century, Wyoming's legal border deviates from the true latitude and longitude lines by up to half of a mile (.8 km) in some spots, especially in the mountainous region along the 45th parallel.[6] 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 97,814 square miles (253,340 km2) and is made up of 23 counties. From the north border to the south border it is 276 miles (444 km);[7] 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.

Wyoming's climate is generally semi-arid and continental (Köppen climate classification BSk), and is drier and windier in comparison to most of the United States with greater temperature extremes. Much of this is due to the topography of the state. Summers in Wyoming are warm with July high temperatures averaging between 85 °F (29 °C) and 95 °F (35 °C) in most of the state. With increasing elevation, however, this average drops rapidly with locations above 9,000 feet (2,700 m) averaging around 70 °F (21 °C). Summer nights throughout the state are characterized by a rapid cooldown with even the hottest locations averaging in the 50–60 °F (10–16 °C) range at night. In most of the state, most of the precipitation tends to fall in the late spring and early summer. Winters are cold, but are variable with periods of sometimes extreme cold interspersed between generally mild periods, with Chinook winds providing unusually warm temperatures in some locations. Wyoming is a dry state with much of the land receiving less than 10 inches (250 mm) of rainfall per year. Precipitation depends on elevation with lower areas in the Big Horn Basin averaging 5–8 inches (130–200 mm) (making the area nearly a true desert). The lower areas in the North and on the eastern plains typically average around 10–12 inches (250–300 mm), making the climate there semi-arid. Some mountain areas do receive a good amount of precipitation, 20 inches (510 mm) or more, much of it as snow, sometimes 200 inches (510 cm) or more annually. The states highest recorded temperature is 114 °F (46 °C) at Basin on July 12, 1900 and the lowest recorded temperature is −66 °F (−54 °C) at Riverside on February 9, 1933.

The number of thunderstorm days vary across the state with the southeastern plains of the state having the most days of thunderstorm activity. Thunderstorm activity in the state is highest during the late spring and early summer. The southeastern corner of the state is the most vulnerable part of the state to tornado activity. Moving away from that point and westwards, the incidence of tornadoes drops dramatically with the west part of the state showing little vulnerability. Tornadoes, where they occur, tend to be small and brief, unlike some of those that occur a little further east.