A post office in Murphy's Settlement opened in 1817, following the annexation of the land to the United States in 1803 as part of the Louisiana Purchase. Missouri became a state in 1821 as part of the Missouri Compromise. In 1822, William Crawford Murphy made a contribution of of land for the installation of the county seat of what was soon to be St. Francois County. Murphy's Settlement was renamed Farmington in 1825, taking the name from the area's rich farm land. Farmington was granted incorporation as a town in 1836 and became a village 20 years later in 1856.