Okmulgee (ōkˌmŭlˈgē) [key], city (1990 pop. 13,441), seat of Okmulgee co., E central Okla., in an oil and farm area; inc. 1900. An agricultural processing center, it has oil and gas wells, a glass industry, and an oil refinery. It was founded on the site of the Creek capital (1868–1907) and boomed with the discovery of oil in 1907. An old Creek council house (1878) is on the town square.