This shapefile contains polygons of every different, mappable version of each county in Massachusetts—plus extinct counties and non-county areas—together with the corresponding attribute table and metadata, from the creation of the first county through 31 December 2000. All changes are dated to the day. The attribute table contains the county names, version numbers, FIPS codes, and the beginning and ending dates for each polygon, plus brief descriptions of the changes and citations to the sources for the changes.