There are 7 US Post Offices in Okmulgee County serving a total of 37,004 residents equating to 5,286 residents per post office. It's estimated that approximately 59,063 packages are handled across the 7 county post offices annually. Okmulgee County is a county located in the U.S. state of Oklahoma. As of the 2010 census, the population was 40,069. The county seat is Okmulgee. Formerly part of the Creek Nation, the county was created at statehood in 1907. The name Okmulgee is derived from the Hitichita (Lower Creek) word okimulgi, meaning \"boiling waters\". Okmulgee County is included in the Tulsa, OK Metropolitan Statistical Area.