In Massachusetts, cities and towns are recognized and recorded as “county subdivisions” by the Census Bureau. County subdivisions are the primary divisions of counties and their equivalent entities for the reporting of decennial census data. A 5-character FIPS code (recorded in COUSUBFP) is used to uniquely identify each county subdivision. Census towns have linework that is often identical to the linework found in MassGIS' munipality boundaries, but also contains many minor discrepancies, particularly along hydrologic and coastal features. The annual Boundary and Annexation Survey (BAS) program attempts to reconcile significant differences in linework (typically discrepancies of 30 feet or more) between Census county subdivisions and the authoritative record, especially where populations are involved. Census towns have been processed and made available to provide a city and town reference for mapping that should align better than the MassGIS municipality boundaries with other Census-derived geographies, including voting districts. Some of the attributes from the MassGIS municipality boundaries have been transcribed into the Census towns attributes.

Town population counts from 1970 to 2010 were obtained from the “City and Town Sortable Rankings” tables provided by the UMass Amherst Donahue Instituteon this Secretary of the Commonwealth’s website. 1960 town population counts were obtained and transcribed from this reportpublished on this state library archives webpageby the Massachusetts Department of Commerce and Development, Bureau of Research and Statistics.