There are 13 US Post Offices in Pittsburg County serving a total of 43,271 residents equating to 3,329 residents per post office. It's estimated that approximately 69,065 packages are handled across the 13 county post offices annually. Pittsburg County is a county located in the U.S. state of Oklahoma. As of the 2010 census, the population was 45,837. Its county seat is McAlester. The county was formed from part of the Choctaw Nation in Indian Territory in 1907. County leaders believed that its coal production compared favorably with Pittsburgh, Pennsylvania at the time of statehood. Pittsburg County comprises the McAlester, OK Micropolitan Statistical Area.