Lake Hefner is a reservoir in northwestern Oklahoma City, Oklahoma. It was built in the 1940s to expand the water supply for the city of Oklahoma City, in part through the labor of German POW's.

Oklahoma City, officially the City of Oklahoma City, and often shortened to OKC, is the capital and most populous city of the U.S. state of Oklahoma. The county seat of Oklahoma County, it ranks 20th among United States cities in population, and is the 8th largest city in the Southern United States. The population grew following the 2010 census and reached 681,054 in the 2020 census. The Oklahoma City metropolitan area had a population of 1,396,445, and the Oklahoma City–Shawnee Combined Statistical Area had a population of 1,469,124, making it Oklahoma's largest municipality and metropolitan area by population.