Dover is a home rule-class city in Mason County, Kentucky, United States. The population was 221 at the 2020 census, down from 252 in 2010. …Dover is a home rule-class city in Mason County, Kentucky, United States. The population was 221 at the 2020 census, down from 252 in 2010. It is part of the Maysville Micropolitan Statistical Area. The town of Dover was laid out by Arthur Fox Jr. in 1818 and possibly named for Dover, England, his father's hometown. A post office was established at Dover in 1833. Dover was incorporated in 1836.