The city of McDonough, located approximately thirty miles southeast of Atlanta, is the seat of government for Henry County. Incorporated on December 17, 1823, the town was named for Commodore Thomas MacDonough, the hero of the Battle of Lake Champlain in the War of 1812 (1812-15). The town was laid out in blocks, with the Henry County Courthouse originally in the center. Like most towns, it was established near its water source. In McDonough, this was known as the "Big Spring," and the city's first waterworks was located there.
In the early years the businesses were centered on an agrarian economy: blacksmith shops, buggy works, sawmills, brick makers, masons, mills for grinding corn and wheat, and, by 1835, cotton gins . There were at least two cotton gins in McDonough: Harkness's on Griffin Street and McGarity's and Welch on Key's Ferry Street. The town blacksmith played a significant role, as he made many of the necessary farm tools as well as useful articles for the homes. McDonough, as a stop, or relay station, for the stagecoach line from New York to New Orleans, also had a number of inns and livery stables.
By 1921 Dr. J. G. Smith had built on the Big Cotton Indian River a hydroelectric plant that furnished the city's electricity for a minimum charge of $1.50 per month. Some of McDonough's more recent enterprises are Dowling Textile Manufacturing Company and Hood's and Carmichael's hosiery mills.
The first churches in McDonough were those of the Methodist (1822), Baptist (1825), and Presbyterian (1827) denominations. Over the years, the number of churches has increased to include Assemblies of God, both Southern and Independent Baptist, Catholic, Christian, Episcopal, and Lutheran congregations, among others.
Henry County Academy, incorporated in 1824, began operating in 1827. By 1831 a female academy also existed. In 1837 the first common school system was adopted, and the academies began to disappear. Modern McDonough has a public school system with primary, elementary, and high schools, as well as a branch of Mercer University, within the city limits.
Among the town's historic sites is the Brown House, a large two-story white house constructed, beginning in 1826, by Andrew McBride, a veteran of the Revolutionary War (1775-83). Now on the National Register of Historic Places, the Brown House is the headquarters of the Genealogical Society of Henry and Clayton Counties, Inc. Another historic house is the Davis-Bryan-Hazlehurst House, built around 1829. McDonough also has a Performing Arts Center, where the Henry Players perform. In May the city hosts the Geranium Festival, and in the fall, the Henry County Fair.
According to the 2010 U.S. census, the population of McDonough is 22,084. Between 2000 and 2010, the city population increased by 160 percent.