Jefferson County is an exurban county located in the U.S. state of Tennessee. As of the 2020 census, the population was 54,683. Its county seat is Dandridge. Jefferson County is part of the Morristown Metropolitan Statistical Area with neighboring Grainger and Hamblen counties. The county, along with the Morristown MSA, is included in the Knoxville-…Jefferson County is an exurban county located in the U.S. state of Tennessee. As of the 2020 census, the population was 54,683. Its county seat is Dandridge. Jefferson County is part of the Morristown Metropolitan Statistical Area with neighboring Grainger and Hamblen counties. The county, along with the Morristown MSA, is included in the Knoxville-Morristown-Sevierville Combined Statistical Area.