Massachusetts is one of 4 US commonwealths.
Massachusetts [ mæsəˈtʃuːsᵻts ] or [ ˌmæsəˈtʃuːzᵻts ] ; officially the Commonwealth of Massachusetts , is the most populous state in the New England region of the northeastern United States . U.S. state . Four states use the term commonwealth rather than state in their full official names .