The Borough of Dartford is a local government district with borough status in Kent, England, in the far north west of the county. Its council is in Dartford. 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 of Essex to the north, across the River Thames, having the longest bridge and tunnel across the river to allow the M25 motorway to cross. According to the 2011 Census, its population was 97,365.