Braintree, officially the Town of Braintree, is a suburban New England city in Norfolk County, Massachusetts, United States. Although officially known as a town, Braintree adopted a municipal charter in 2008, with a mayor-council form of government, and is considered a city under Massachusetts law. The population was 35,744 at the 2010 census. The city is part of the Greater Boston area with access to the MBTA Red Line, and is a member of the Metropolitan Area Planning Council's South Shore Coalition. The first mayor of Braintree was Joe Sullivan who served until January, 2020.