Marshall County is a county located in the U.S. state of Kentucky. As of 2000, the population was 30,125. The 2007 Census Bureau population estimate was 31,258. Its county seat is Benton. It was a dry county until 2004, when residents of Calvert City voted to allow sales of liquor by the drink in restaurants. It is the only Purchase Area county to not border another state.
Marshall County was formed by the Kentucky legislature in 1842 from part of Calloway County. The first settlers came about 1818, when the area was bought from the Chickasaw Indians as part of the Jackson Purchase. The Native Americans then moved to new lands west of the Mississippi River. Marshall County was named in honor of Chief Justice John Marshall, who had died shortly before the county's creation.
From its settlement until the 1930s, Marshall County was nearly completely agricultural.
In the 1940s, the Tennessee Valley Authority created Kentucky Lake, which brought tourism to the county with lake shore resorts. The Kentucky Dam's cheap and plentiful electricity also attracted chemical and manufacturing plants, mostly in the Calvert City area. However, the creation of the lake destroyed two historic Marshall County towns - Birmingham, located six miles north of the present town of Fairdealing, and Gilbertsville, which was at the dam's site. Gilbertsville was rebuilt to the west of its original location. Birmingham residents had to move elsewhere. Gilbertsville was an incorporated town until the 1970s, when its charter was dissolved by public vote. Kentucky Lake (created on the Tennessee River) and Lake Barkley (created on the Cumberland River) form one of the largest man-made bodies of water in the world.
Historically, Marshall County has been a stronghold of the Democratic Party. Since the founding of the county, Democrats have dominated county politics. At present, all elected county officials are Democrats, with the exception of one.