the borough of dartford is a local government district in the north-west of the county of kent, england. its council is based in the town of dartford. it is part of the contiguous london urban area. it borders the borough of gravesham to the east, sevenoaks district to the south, the london borough of bexley to the west, and the thurrock unitary authority in essex to the north, across the river thames. the borough was formed on 1 april 1974 by the merger of the municipal borough of dartford, the swanscombe urban district, and part of the dartford rural district. according to the 2011 census, its population was 97,365.