Demopolis's the largest city in Marengo County, Alabama, United States. At the 2000 census the population was 7,540. History Demopolis, the City of the People, was founded by a group of French expatriates, many of whom came to the United States after fleeing a slave rebellion on the sugar plantations of Haiti. Arriving first in Philadelphia, Pennsylvania, they petitioned the U.S. Congress to sell them property and received permission to buy four townships at $2 per acre with the provision that… (More on Demopolis)