Demopolis is the largest city in Marengo County, Alabama, United States. The population was 7,483 at the time of the 2010 United States Census.The city lies at the confluence of the Black Warrior and Tombigbee rivers. It is situated atop a cliff composed of the Demopolis Chalk Formation, known locally as White Bluff, on the east bank of the Tombigbee River. It is at the center of Alabama's Canebrake region and is also within the Black Belt.Demopolis was founded after the fall of Napoleon's Empire and named by a group of French expatriates, a mix of exiled Bonapartists and other French migrants who had settled in the United States after the overthrow of the colonial government in Saint-Domingue following the failed Saint-Domingue expedition. The name, meaning in Greek "the People's City" or "City of the People", was chosen to honor the democratic ideals behind the endeavor. First settled in 1817, it is one of the oldest continuous settlements in Alabama.