Louisville is a major city and the largest city in the U.S. state of Kentucky and the county seat of Jefferson County.

Since 2003, the city's borders have been coterminous with those of the county because of a city-county merger. The city's total consolidated population at the 2010 census was 741,096 (Louisville's balance total, 602,011, excludes semi-autonomous towns and is the population listed in most sources and national rankings). As of 2010, the Louisville metropolitan area (MSA) had a population of 1,307,647 ranking 42nd nationally. The metro area includes Louisville-Jefferson County and 12 surrounding counties, eight in Kentucky and four in Southern Indiana (see Geography below). The Louisville Combined Statistical Area, having a population of 1,451,564, includes the MSA, Hardin County and Larue County in Kentucky, and Scott County, Indiana.

An important internal shipping port in the 19th century, Louisville today is best known as the location of the Kentucky Derby, the first of three annual thoroughbred horse races making up the Triple Crown.