A county or group of contiguous counties (towns and cities in New England) that has (1) atleast one city with 50,000 or more in habitants; or (2) an urbanised area of 50,000 inhabitants and a total population of 100,000 or more inhabitants (75,000 in New England). These areas are defined by the U.S.Office of Management and Budget. The contiguous counties or other jurisdictions to be included in an MSA are those that, according to certain criteria, are essentially metropolitan in character and are socially and economically integrated with the central city or urbanised area.