The U.S. state ofWyoming lies in theMountain West subregion of theWestern United States and has a varied geography. It is bordered byMontana to the north and northwest,South Dakota andNebraska to the east,Idaho to the west,Utah to the southwest, andColorado to the south. Wyoming is the least populous U.S. state^[1] and has the second-lowest population density behindAlaska.

Wyoming's western half is covered mostly by the ranges and rangelands of theRocky Mountains, while the eastern half of the state is high-elevationprairie called theHigh Plains. It is drier and windier than the rest of the country, being split betweensemi-arid andcontinental climates with greater temperature extremes. Almost half of the land in Wyoming is owned by thefederal government, generally protected for public uses. The state ranks 6th by area and fifth by proportion of a state's land owned by the federal government.^[2] Federal lands within Wyoming include two national parks (Grand Teton andYellowstone), two national recreation areas, two national monuments, several national forests, historic sites, fish hatcheries, and wildlife refuges.

Wyoming's climate is generallysemi-arid andcontinental (Köppen climate classificationBSk), 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 80 and 90 °F (27 and 32 °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, withChinook winds providing unusually warm temperatures in some locations.^[3]

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 theBig Horn Basin averaging 5–8 inches (130–200 mm), making the area nearly a truedesert. The lower areas in the North and on the eastern plains typically average around 10–12 inches (250–300 mm), making the climate theresemi-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 state's highest recorded temperature is 114 °F (46 °C) atBasin on July 12, 1900,^[4][5] and the lowest recorded temperature is −66 °F (−54 °C) atRiverside on February 9, 1933.^[5]

The number ofthunderstorm 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 totornado 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 farther east. The most destructive tornado to occur in Wyoming happened on July 16, 1979, in Cheyenne and caused one death and 40 injuries.^[6][7]

As specified in the designating legislation for theTerritory of Wyoming, Wyoming's borders are lines oflatitude41°N and45°N, andlongitude 104°3'W and 111°3'W (27 and 34 west of theWashington Meridian)—ageodesic quadrangle.^[17] Due to surveying inaccuracies during the 19th century, Wyoming's legal border deviates from the truelatitude andlongitude lines by up to one-half mile (0.80 km) in some spots, especially in the mountainous region along the45th parallel.^[18] Wyoming is bordered on the north byMontana, on the east bySouth Dakota andNebraska, on the south byColorado, on the southwest byUtah, and on the west byIdaho. 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); 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.

TheGreat Plains meet theRocky Mountains in Wyoming. The state is a greatplateau broken by manymountain ranges. Surface elevations range from the summit ofGannett Peak in theWind River Mountain Range, at 13,804 feet (4,207 m), to theBelle Fourche River valley in the state's northeast corner, at 3,125 feet (952 m). In the northwest are theAbsaroka,Owl Creek,Gros Ventre,Wind River, and theTeton ranges. In the north central are theBig Horn Mountains; in the northeast, theBlack Hills; and in the southern region theLaramie,Snowy, andSierra Madre ranges.

The Snowy Range in the south central part of the state is an extension of the ColoradoRockies both in geology and in 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 13,000 ft (4,000 m) 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 Teton Range in the northwest extends for 50 miles (80 km), part of which is included inGrand Teton National Park. The park includes theGrand Teton, the second highest peak in the state.

TheContinental Divide spans north–south across the central portion of the state. Rivers east of the divide drain into theMissouri River Basin and eventually theGulf of Mexico. They are theNorth Platte,Wind,Big Horn and theYellowstone rivers. TheSnake River in northwest Wyoming eventually drains into theColumbia River and the Pacific Ocean, as does theGreen River through theColorado River Basin.

The Continental Divide forks in the south central part of the state in an area known as theGreat Divide Basin where water that precipitates onto or flows into it cannot reach an ocean—itall sinks into the soil and eventually evaporates.

Several rivers begin in or flow through the state, including the Yellowstone River, Bighorn River, Green River, and the Snake River.

Much of Wyoming is covered with large basins containing different eco-regions, from shrublands to smaller patches of desert.^[19] Regions of the state classified as basins contain everything from large geologic formations to sand dunes and vast unpopulated spaces.^[20] Basin landscapes are typically at lower elevations and include rolling hills, valleys, mesas, terraces and other rugged terrain, but also include natural springs as well as rivers and artificial reservoirs.^[21] They have common plant species such as various subspecies ofsagebrush,juniper and grasses such aswheatgrass, but basins are known for their diversity of plant and animal species.^[19]

Wyoming has 32 named islands; the majority are inJackson Lake andYellowstone Lake, withinYellowstone National Park in the northwest portion of the state. TheGreen River in the southwest also contains a number of islands.

The state of Wyoming has 23counties. Thirteen were there when Wyoming became a state in 1890 and ten more have been created since then.^[22]

Wyoming license plates have a number on the left that indicates the county where the vehicle is registered, ranked by an earlier census.^[24] Specifically, the numbers are representative of the property values of the counties in 1930.^[25] The county license plate numbers are:

The State of Wyoming has 99incorporated municipalities.

In 2005, 50.6% of Wyomingites lived in one of the 13 most populous Wyoming municipalities.

TheUnited States Census Bureau has defined twoMetropolitan Statistical Areas (MSA) and sevenMicropolitan Statistical Areas (MiSA) for the State of Wyoming. In 2008, 30.4% of Wyomingites lived in either of theMetropolitan Statistical Areas, and 73% lived in either aMetropolitan Statistical Area or aMicropolitan Statistical Area.

• Rocky Mountains
• Geography of Montana
• Continental Divide

• Geography of Wyoming

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