Dover is the capital and second-most populous city of the U.S. state of Delaware. It is also the county seat of Kent County and the principal city of the Dover metropolitan statistical area, which encompasses all of Kent County and is part of the Philadelphia–Wilmington–Camden, PA–NJ–DE–MD, combined statistical area. It is located on the St. Jones River in the Delaware River coastal plain. It was named by William Penn for Dover in Kent, England. As of 2020, its population was 39,403.