Louisville ( , or ) 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 system across 13 states. Today, the city is known as the home of the Kentucky Derby, Kentucky Fried Chicken, the University of Louisville and its Louisville Cardinals athletic teams, Louisville Slugger baseball bats, and three of Kentucky's six "Fortune" 500 companies. Its main airport is also the site of United Parcel Service's worldwide air hub. 

Since 2003, Louisville's borders have been the same as those of Jefferson County because of 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 2014 census estimate was 760,026. However, the balance total of 612,780 excludes other incorporated places and semiautonomous towns within the county and is the population listed in most sources and national rankings.
what rank of population does it have?
29th-most populous city in the United States