Quincy ( ), known as Illinois's "Gem City", is a city in and the county seat of Adams County, Illinois, United States, located on the Mississippi River. The 2020 census counted a population of 39,463 in the city itself, down from 40,633 in 2010. As of July 1, 2015, the Quincy Micro Area had an estimated population of 77,220. During the 19th century, Quincy was a thriving transportation center as riverboats and rail service linked the city to many destinations west and along the river. It was Illinois' second-largest city, surpassing Peoria in 1870. The city has several historic districts, including the Downtown Quincy Historic District and the South Side German Historic District, which display the architecture of Quincy's many German immigrants from the late 19th century. History Early history Quincy's location along the Mississippi River has attracted settlers for centuries. The French became the first European presence to colonize the region, after Louis Jolliet, Jacques Marquette, Jamison Knapp and the La Salle Expeditions explored the Upper Mississippi River Valley. Fur goods became a valuable commodity of the region, and European explorers and merchants alike were attracted to the prospects of the growing fur trade of the North American frontier. The Mississippi River, acting as a superhighway for transporting goods downstream, became the area's most vital transportation asset. Following the events of the Seven Years' War, which ended in 1763, Great Britain took control of New France, including that of the Illinois Territory. The Illinois Territory changed hands again a few decades later during the American Revolutionary War. 19th century After the War of 1812, the American government granted military tracts to veterans as a means to help populate the West. Peter Flinn, having acquired the land from veteran Mark McGowan for his military service in 1819, ended up selling of land acquisitions to Moravia, New York native John Wood for $60. John Wood later founded Quincy, which at the time was coined Bluffs, Illinois. In 1825, Bluffs renamed their community Quincy and became the seat of government for Adams County, both named after newly elected President John Quincy Adams. In addition, they originally named the town square John Square until eventually changing it to Washington Square. In June 1834, Quincy was incorporated, with Archibald Williams, Joseph T. Holmes, S. W. Rogers, Levi Wells, and Michael Mast elected as trustees. Quincy incorporated as a city in 1840, with Ebenezer Moore