The French introduced legalized slavery into their colonies in New France near the Great Lakes and the Mississippi River. After the port of New Orleans, to the south, was founded in 1718, more African slaves were imported to the Illinois Country for use as agricultural or mining laborers. By the mid-eighteenth century, slaves accounted for as many as a third of the population in that area.[29] Slavery existed in colonial Louisiana continuously during the French (1699 – 1763, and 1800 – 1803) and Spanish (1763 – 1800) periods of government.