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 other two being Fayette and Lincoln). The county is named for 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 (the official long form) or simply Louisville Metro (the official short form). That made it the largest city in Kentucky.
