There are 4 US Post Offices in Marshall County serving a total of 31,177 residents equating to 7,794 residents per post office. It's estimated that approximately 49,762 packages are handled across the 4 county post offices annually. Marshall County is a county located in the U.S. state of Kentucky. As of the 2010 census, the population was 31,448. Its county seat is Benton. It was a dry county until July 28, 2015, when residents voted for the county to go \"wet\". It is the only Purchase Area county to not border another state. Marshall County was named Kentucky's \"Best County to Live In\" ten years in a row, from 1999\u20132009."