Casper is a city in, and the county seat of, Natrona County, Wyoming, United States. Casper is the second largest city in the state, with the population was estimated at 57,931 as of 2019. Only Cheyenne, the state capital, is larger. Casper is nicknamed "The Oil City" and has a long history of oil boomtown and cowboy culture, dating back to the development of the nearby Salt Creek Oil Field.
Casper is located in east-central Wyoming at the foot of Casper Mountain, the north end of the Laramie Mountain Range, and along the North Platte River.