There are 3 US Post Offices in Irwin County serving a total of 7,697 residents equating to 2,566 residents per post office. It's estimated that approximately 12,285 packages are handled across the 3 county post offices annually. Irwin County is a county located in the U.S. state of Georgia. As of the 2010 census, the population was 9,538. The county seat is Ocilla. The county was created on December 15, 1818. It was named for Governor Jared Irwin. In the last years of the American Civil War, Irwin County gained the nickname of the Republic of Irwin due to the Unionism of many of its residents. The location where Jefferson Davis was captured  is located in Irwin County near Irwinville.