Braintree, officially the Town of Braintree, is a suburban city in Norfolk County, Massachusetts, United States. Although officially known as a town, Braintree adopted a municipal charter, effective 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 town is part of the Greater Boston area with access to the MBTA Red Line and is a member of the Metropolitan Area Planning Commission's South Shore Coalition. The first and current mayor of Braintree is Joe Sullivan.