Irwin County, in central Georgia, is the state's forty-first county, created in 1818 from land acquired from Creek Indians in 1814 by the Treaty of Fort Jackson. The county, one of seven created by the state legislature in 1818, once encompassed much more territory. Counties carved from it were Lowndes and Thomas (1825), Worth (1853), Coffee (1854), Berrien (1856), Wilcox (1857), Tift and Turner (1905), and Ben Hill (1906). It was named for Jared Irwin, a governor of Georgia most famous for rescinding the fraudulent Yazoo Act.
Until the Indian treaties were signed, periodic conflict occurred between the whites and Indians. The county was divided into sixteen land districts, each composed of several hundred lots, in 1818. There were some settlers in the area, most of them from other parts of the South, even before the county was formed. Much of the land was virgin pine forest. Many of the original settlers lived first by subsistence farming and hunting and moved later into cattle ranching after establishing their homesteads. Eventually, settlers produced cotton and fruit, as well as cattle, for the market.
The first county seat was developed on a location designated by the state legislature and named Irwinville. It was the seat of government from 1831 until 1907, when the county's voters elected to change the location to the bustling town of Ocilla, ten miles southeast of Irwinville. Ocilla, founded around 1880 and incorporated in 1897, nearly tripled in population soon after it was connected by railroad to Fitzgerald and incorporated in 1897. Today, Ocilla is the only incorporated city in Irwin County. (Irwinville was incorporated from 1857 to 1995.)
From 1820 to 1822 the county's court hearings were held at the home of resident David Williams, and from 1822 through 1839 they were held in a schoolhouse on the property of a Scots settler, Murdock McDuffie. The first official courthouse was built in Irwinville in 1839 and was followed in 1854 and 1883 by newer buildings. It is believed that the business of the county was carried on in these buildings, even after the county seat was relocated, until the current courthouse (the county's fourth official one) was completed in 1910. Major renovations were made to it in 1972.
The county's most famous incident occurred during the Civil War (1861-65). Confederate president Jefferson Davis was captured a mile north of Irwinville, by Union forces, in 1865. The spot where he was surrounded is marked in the Jefferson Davis Memorial Historic Site, a thirteen-acre park that features a museum, hiking trail, and picnic facilities.
Irwin County also has an important place in the history of shape-note music. It is the site of the first documented shape-note singing convention in Georgia, the South Georgia Singing Convention, which was founded in 1875 by William Jackson Royal.
Other communities in the county are Abba, Holt, Lax, Mystic (incorporated from 1903 to 1995), Osierfield (incorporated from 1912 to 1995), and Wray.
Notable residents of Irwin County include writer Amy Blackmarr, a Georgia Author of the Year for 2004.
According to the 2010 U.S. census, the population of Irwin County is 9,538, a decrease from the 2000 population of 9,931.