Farmington is a city in St. Francois County located about 75 miles (121 km) southwest of St. Louis in the Lead Belt region in Missouri. As of the 2020 census, the population was 18,217. It is the county seat of St. Francois County. Farmington was established in 1822 as Murphy's Settlement, named for William Murphy of Kentucky, who first visited the site in 1798. When St. Francois County was organized, the town was briefly called St. Francois Court House and later renamed to Farmington.