Louisville is the most populous city in the Commonwealth of Kentucky, sixth-most populous city in the Southeast, and the 27th-most-populous city in the United States. By land area, it is the country's 24th-largest city, although by population density, it is the 265th most dense city. Louisville is the historical county seat and, since 2003, the nominal seat of Jefferson County, on the Indiana border. Named after King Louis XVI of France, Louisville was founded in 1778 by George Rogers Clark, making it one of the oldest cities west of the Appalachians. With the nearby Falls of the Ohio as 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 (9,700 km) system across 13 states. Today, the city is known as the home of boxer Muhammad Ali, the Kentucky Derby, Kentucky Fried Chicken, the University of Louisville and its Cardinals, Louisville Slugger baseball bats, and Fortune 500 company Humana. Louisville Muhammad Ali International Airport, the city's main commercial airport, hosts UPS's worldwide hub. Since 2003, Louisville's borders have been the same as those of Jefferson County, after a city-county merger. The official name of this consolidated city-county government is the Louisville/Jefferson County Metro Government, abbreviated to Louisville Metro. Despite the merger and renaming, the term "Jefferson County" continues to be used in some contexts in reference to Louisville Metro, particularly including the incorporated cities outside the "balance" which make up Louisville proper. The city's total consolidated population as of the 2020 census was 782,969. However, the balance total of 633,045 excludes other incorporated places within the county and is the population listed in most sources and national rankings. The Louisville-Jefferson County, KY-IN Metropolitan Statistical Area (MSA) includes Louisville-Jefferson County and 12 surrounding counties, seven in Kentucky and five in Southern Indiana. As of 2023, the MSA had a population of 1,365,557, the 43rd largest in the nation.