Jefferson County, Kentucky

Jefferson County
Consolidated city-county
Jefferson County Courthouse (now Louisville Metro Hall) in downtown Louisville
Seal
Location within the U.S. state of Kentucky
Kentucky's location within the U.S.
Coordinates: 38°11′N 85°40′W / 38.19°N 85.66°W / 38.19; -85.66
Country	United States
State	Kentucky
Founded	1780
Named for	Thomas Jefferson
Seat	Louisville
Largest city	Louisville
Area
• Total	398 sq mi (1,030 km2)
• Land	380 sq mi (1,000 km2)
• Water	17 sq mi (40 km2)  4.3%
Population  (2020)
• Total	782,969
• Estimate  (2023)	772,144
• Density	2,000/sq mi (760/km2)
Time zone	UTC−5 (Eastern)
• Summer (DST)	UTC−4 (EDT)
Congressional districts	3rd, 2nd
Website	louisvilleky.gov

Jefferson County is located in the north central portion of the U.S. state of Kentucky. As of the 2020 census, the population was 782,969.^[1] It is the most populous county in the commonwealth (with more than twice the population of second ranked Fayette County).

Since a city-county merger in 2003, the county's territory, population and government have been coextensive with the city of Louisville, which also serves as county seat. The administrative entity created by this merger is the Louisville/Jefferson County Metro Government,^[2] abbreviated to Louisville Metro.^[3]

Jefferson County is the anchor of the Louisville-Jefferson County, KY-IN Metropolitan Statistical Area, locally referred to as Kentuckiana.