Louisville LOO-ə-vəl, /ˈlʊvəl/  LUUV-əl or /ˈluːiːvɪl/ ) is the largest city in the Commonwealth of Kentucky and the 29th-most populous city in the United States. It is one of two cities in Kentucky designated as first-class, the other being the state's second-largest city of Lexington. Louisville is the historical seat and, since 2003, the nominal seat of Jefferson County.Louisville was founded in 1778 by George Rogers Clark and is named after King Louis XVI of France, making Louisville one of the oldest cities west of the Appalachian Mountains. Sited beside the Falls of the Ohio, the only major obstruction to river traffic between the upper Ohio River and the Gulf of Mexico, the settlement first grew as a portage site. It was the founding city of the Louisville and Nashville Railroad, which grew into a 6,000-mile system across 13 states.