Potosi is a city in Washington County, Missouri, United States. Potosi is about 10 miles North of Belgrade. The estimated population in July 2008 was 2,698. It was 2,662 at the 2000 census. It is the county seat of Washington County. The city was founded in 1783 by Moses Austin and was named after the Bolivian silver-mining city of Potosí.
Potosi is located at 37°56′16″N 90°46′55″W / 37.93778°N 90.78194°W / 37.93778; -90.78194 (37.937881, -90.781932). According to the United States Census Bureau, the city has a total area of 2.2 square miles (5.6 km²), all of it land.
A lead mining settlement at this spot, "Mine á Breton" or Mine au Breton, was founded between 1760 and 1780 by Francis Azor, of Brittany, France. Moses Austin came here in 1798 with his family, including his son Stephen F. Austin. Moses obtained a grant of 7,153 arpents of land from the Spanish Empire and started large-scale mining operations, building his town to support it. Moses named the town after Potosí in Bolivia, which was famous for its vast silver mines. Austin's tomb and the foundation of his home Durham Hall can still be seen. Another mining entrepreneur in Potosi at the time of Moses Austin was James Bryan. Firmin Desloge, who emigrated from Nantes, France in 1822 located in Potosi and established a mercantile, distillery, fur trading and lead smelting business. The Desloge lead mining business Desloge Consolidated Lead Company was later relocated to Desloge, MO