Bristol County, Massachusetts Bay Province (New England)

Bristol County, originally a part of Plymouth Colony, was formed on 2 June 1685, along with the counties of Plymouth and Barnstable, by the legislature of Plymouth Colony in preparation for its 7 October 1691 annexation by the Massachusetts Bay Province. At its creation, Bristol County was composed of the towns of Taunton, Bristol, Dartmouth, Freetown, Little Compton, Rehoboth and Swansea.

Bristol County is adjacent to the state of Rhode Island and lost the towns of Bristol, Barrington, and Warren in 1746 when they were awarded to Rhode Island, forming that state's Bristol County, as part of a long-running boundary dispute. At the same time, Cumberland, Rhode Island was carved out of Attleborough, Massachusetts and annexed to Providence County, Rhode Island, and Tiverton and Little Compton were transferred to Newport County, Rhode Island. East Freetown was officially purchased by Freetown, Massachusetts, from Tiverton in 1747, and so remained on the Massachusetts side. In 1862, part of Seekonk (now East Providence, Rhode Island) and the entirety of East Pawtucket were transferred to Providence County, Rhode Island. At the same time, land ceded from Rhode Island was added to Fall River and Westport.

Over time, communities within the Massachusetts Bristol County were subdivided, forming new towns and villages, and the boundaries between Plymouth and Bristol counties changed on 1 June 1867 when Taunton and Lakeville redefined their border, and on 9 April 1836, when Rochester and Fairhaven redefined theirs.