Downloads
Overview
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’ municipality 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. MassGIS processed and makes available Census towns 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.
The Census towns polygons are named CENSUS2020TOWNS_POLY
The Census towns outlines are named CENSUS2020TOWNS_ARCS
Attributes
Attributes for polygons
| Field | Length | Type | Description |
| STATEFP | 2 | String | 2020 Census state FIPS code |
| COUNTYFP | 3 | String | 2020 Census county FIPS code |
| COUSUBFP | 5 | String | 2020 Census county subdivision FIPS code |
| COUSUBNS | 8 | String | 2020 Census ANSI feature code for the county subdivision |
| GEOID | 10 | String | 2020 Census county subdivision identifier; a concatenation of 2020 state FIPS code, county FIPS code, and county subdivision FIPS code |
| NAMELSAD | 100 | String | Name and translated legal/statistical area description code for the 2020 Census county subdivision |
| LSAD | 2 | String | Translated legal/statistical area description code for the 2020 Census county subdivision |
| CLASSFP | 2 | String | 2020 Census FIPS class code |
| MTFCC | 5 | String | MAF/TIGER Feature Class Code (G4040) |
| CNECTAFP | 3 | String | 2020 Census combined New England city and town area code |
| NECTAFP | 5 | String | 2020 Census New England city and town area code |
| NCTADVFP | 5 | String | 2020 Census New England city and town area division code |
| FUNCSTAT | 1 | String | 2020 Census functional status |
| ALAND | Double | 2020 Census land area in square meters | |
| AWATER | Double | 2020 Census water area in square meters | |
| INTPTLAT | 11 | String | 2020 Census latitude of the internal point |
| INTPTLON | 12 | String | 2020 Census longitude of the internal point |
| TOWN | 25 | String | Official name of the city/town |
| TOWN_ID | Integer | The town ID assigned to the official town name | |
| FIPS_STCO | Integer | Federal Information Processing Standard (FIPS) State/County Code | |
| COUNTY | 15 | String | Name of the county the town exists within |
| TYPE | 2 | String | C = City; T = Town; TC = Town with City form of government |
| FOURCOLOR | Integer | Codes (1,2,3,4) allowing shading of all towns using 4 symbols (based on four-color theorem, where no adjacent polygons have the same symbol) | |
| AREA_ACRES | Double | Area of the town calculated in acres | |
| SQ_MILES | Double | Area of the town calculated in square miles | |
| Shape_Length | Double | Perimeter of the town in meters | |
| Shape_Area | Double | Area of the town in square meters | |
| POP1960 | Integer | US Census population for the town in 1960 | |
| POP1970 | Integer | US Census population for the town in 1970 | |
| POP1980 | Integer | US Census population for the town in 1980 | |
| POP1990 | Integer | US Census population for the town in 1990 | |
| POP2000 | Integer | US Census population for the town in 2000 | |
| POP2010 | Integer | US Census population for the town in 2010 | |
| POP2020 | Integer | 2020 Census count of population as determined by PL94-171 demographics report for redistricting, aggregated from blocks | |
| POPCH10_20 | Integer | Change in population for the town from 2010 to 2020 | |
| HOUSING20 | Integer | 2020 Census count of housing units as determined by PL94-171 demographics report for redistricting, aggregated from blocks |
** Town population counts from 1970 to 2010 were obtained from the “City and Town Sortable Rankings” tables provided by the UMass Amherst Donahue Institute on this Secretary of the Commonwealth’s website. Town population counts from 1960 were obtained and transcribed from this report published on this state library archives webpage by the Massachusetts Department of Commerce and Development, Bureau of Research and Statistics.
Attribute for arcs
| OUTLINE | State = 1, Coast = 4, Towns = 17 |
Processing
MassGIS downloaded Census 2020 geographic data from the Census Bureau’s website using this link:
Towns - https://www2.census.gov/geo/tiger/TIGER2020/COUSUB/tl_2020_25_cousub.zip
(A full set of TIGER/Line shapefiles and relationship files available for download from the Census Bureau is listed here). This statewide shapefile was extracted from the zip file and projected into the standard MassGIS data library projection (Massachusetts State Plane NAD 1983 Mainland, Meters).
The downloaded Census geography files for Massachusetts included areas that extend into coastal waters. MassGIS incorporated a generalized coastline by removing areas flagged as water along the coast (using the LWFLAG attribute in the Census Faces data), interactively reviewing and editing select locations that remained visually incongruous with the 2021 aerial imagery, and re-adding a small number of modified areas identified as being entirely water but containing a non-zero population (indicative of “transient units” like house boats).
MassGIS reviewed attributes for function and utility; nearly all native attributes were retained. Additional attributes were added to the geography file as appropriate to facilitate anticipated user needs.
Use limitations
As stated in section 1.1 of the technical documentation… “No warranty, expressed or implied, is made with regard to the accuracy of the data in the TIGER/Line Shapefiles, and no liability is assumed by the United States Government in general, or the Census Bureau specifically, as to the positional or attribute accuracy of the data. The boundary information in the TIGER/Line Shapefiles is for statistical data collection and tabulation purposes only. Their depiction and designation for statistical purposes does not constitute a determination of jurisdictional authority or rights of ownership or entitlement and are not legal land descriptions. TIGER/Line® is a registered trademark of the Census Bureau. TIGER/Line cannot be used as or within the proprietary product names of any commercial product including or otherwise relevant to Census Bureau data and may only be used to refer to the nature of such a product.”
If there are any questions about these geographic layers not answered by the Census Bureau 2020 TIGER/Line shapefiles documentation, please direct them to daniel.marrier@mass.gov.