Dover serves as the capital and second-most populous city in the U.S. state of Delaware, situated within Kent County on the St. Jones River in the Delaware River coastal plain. It functions as the county seat and the principal city of the Dover metropolitan statistical area, which encompasses all of Kent County and falls within the broader Philadelphia metropolitan region. The city's central location and relative safety from British raiders historically contributed to its selection as the state capital.

Founded in 1683 by William Penn as the court town for newly established Kent County, Dover was officially laid out by a special commission of the Delaware General Assembly in 1717. The state capital moved here from New Castle in 1777 due to its strategic position. After the assembly met successively in various locations, it permanently settled in Dover in October 1781, establishing the city's enduring political significance.

The Green remains the heart of Dover's historic district, hosting the Delaware Supreme Court and Kent County Courthouse. The city is home to numerous sites listed on the National Register of Historic Places, including the John Dickinson House, Old Statehouse, and Victorian Dover Historic District. It was also the home of Caesar Rodney, a popular wartime leader during the American Revolution, whose cenotaph stands near The Green.

Dover's heritage includes a significant Quaker community that encouraged emancipation efforts in the early 19th century, alongside its role as a stop on the Underground Railroad. The city features diverse historic architecture and landmarks such as the Bradford-Loockerman House and Eden Hill. Its history is deeply tied to the American Revolution and the complex social dynamics surrounding slavery in the region.

As of 2020, the population was 39,403, with estimates reaching 40,191 by 2024. The state government is the largest employer, followed by Dover Air Force Base and major manufacturers like Kraft Foods and Procter & Gamble. The city experiences a humid subtropical climate with hot summers and mild winters, averaging 13.2 inches of snow annually.