Jefferson County, Kentucky

Jefferson County, Kentucky
Jefferson County Courthouse (now Louisville Metro Hall) in downtown Louisville
Seal
Location in the U.S. state of Kentucky
Kentucky's location in the U.S.
Founded	1780
Named for	Thomas Jefferson
Seat	Louisville
Largest city	Louisville
Area
• Total	398 sq mi (1,031 km2)
• Land	380 sq mi (984 km2)
• Water	17 sq mi (44 km2), 4.3%
Population (est.)
• (2015)	763,623
• Density	1,948/sq mi (752/km²)
Congressional districts	3rd, 4th
Time zone	Eastern: UTC-5/-4
Website	www.louisvilleky.gov

Jefferson County is a county located in the U.S. state of Kentucky. As of the 2010 census, the population was 741,096. It is the most populous county in Kentucky and is more than twice as large as the second most populous, Fayette. The county was formed in 1780 and named for future President Thomas Jefferson, who was Governor of Virginia at the time.

In 2003, its government merged with that of its largest city and county seat, Louisville, forming a new entity, the Louisville/Jefferson County Metro Government (official long form) or Louisville Metro (official short form). Whenever possible, the metro government generally avoids any self-reference including the name "Jefferson County" and has even renamed the Jefferson County Courthouse as "Metro Hall".

Jefferson County is the anchor of the Louisville-Jefferson County, KY-IN Metropolitan Statistical Area.

Jefferson County was organized in 1780 and one of the first three counties formed out of the original Kentucky County, which was still part of Virginia at the time (the others being Fayette and Lincoln). The county is named for Thomas Jefferson, who was governor of Virginia at the time.

The last major American Indian raid in present-day Jefferson County was the Chenoweth Massacre on July 17, 1789.

Prior to the 2003 merger, the head of local government was the County Judge/Executive, a post that still exists but now has few powers. The office is currently held by Queenie Averette.