OVERVIEW

This political boundary datalayer has been created from latitude and longitue coordinates found in the 68-volume Harbor and Lands Commission Town Boundary Atlas.  This Atlas series, and updates since it was published, describes the legal boundary for each of the 351  municipalities in Massachusetts.  These coordinates were recorded from surveys of the location of each boundary marker around the periphery of each community.  Each survey was tied into higher order monumented survey control points.  The Atlases also include detailed descriptions of each community's boundary and location maps for each of the original boundary marker locations.  The original surveys were conducted in the 1890s.  The Atlas series was published in the early 1900s and has since been updated by the Survey Section of the Massachusetts Highway Department with changes as they are approved by the legislature.

MassGIS staff collaborated closely with staff from the Survey Section during the development of this data layer.  MassGIS staff keyed the coordinates into a database; that data entry was double-checked by staff from the Survey Section.  Staff from the Survey Section then converted the latitude/longitude coordinates to the NAD83 datum and also created a version of the coordinates in state plane coordinates with units of meters.  MassGIS used the state plane coordinates to "generate" points in ArcGIS.  Boundary arcs from the existing USGS-derived municipal boundary data layer were then snapped to the survey-derived points.  The differences between the municipal boundary arcs digitized from those on the USGS quads and those created by snapping to the survey-derived coordinates are typically plus or minus 12 feet, although these differences are sometimes less and sometimes more.  Some municipal boundary arcs (about 15% of the total) follow the edge of a road or rail right-of-way or a stream or river channel.  In these cases, the new boundary arcs were "heads up" digitized based on features visible on the statewide 1:5,000 color orthos from imagery flown in 2001.   How each boundary arc was developed is identified in the arc attributes, as described below.

According to staff from the Survey Section, based on their knowledge of historical surveying methods, of changes to the North American Datum at its various versions, and of the algorithms used to convert coordinates from one datum to another, the individual boundary marker coordinates are on average approximately plus/minus three feet.  Some points may be more accurate than this and some points are definitely less.  The information available in this data layer CANNOT be used to determine the definitive locations of either individual boundary markers or of a specific municipal boundary.  Such determinations can only be made by a professional land surveyor.  Note that as part of its assistance to surveyors, the MassHighway Department makes available the coordinate information for the individual town boundary survey points that were the basis for this data layer on their "Survey Control and Layout Plans" web site at http://www.mhd.state.ma.us/mhds (see the "Town Corners" tab).

For communities with a coastal boundary, MassGIS collaborated with the Massachusetts Water Resources Authority and the Department of Environmental Protection to complete a 1:12,000 scale coastline.

Note that the 351 communities are the official municipal names, not including "villages" or other sections of towns. The Secretary of State's office has prepared a web page listing the Unincorporated and Unofficial Names of Massachusetts Communities. Also see the List of Town Numbers and Names and Towns Index Map.

This layer comprises four separate feature classes, stored in ArcSDE:

• TOWNSSURVEY_POLY - Polygons representing inland and offshore areas
• TOWNSSURVEY_POLYM - Multi-part polygons representing inland and offshore areas, with one feature for each of the 351 municipalities.
  
• TOWNSSURVEY_ARC - Lines representing municipal boundaries and coastline
  
• TOWNSSURVEY_PT - Points representing survey points
  

These four feature classes are organized in TOWNSSURVEY SDE feature dataset, which includes the TOWNSSURVEY_Topology; rules have been created to enforce spatial relationships among the POLY, ARC and PT  layers.

MassGIS considers this the first release of this layer. Future work will consist of (1) improving the accuracy of boundaries identified as following a road right of way (see "Attributes" section below for description of BND_QUAL where attribute value = 2) and (2) adding offshore boundaries to the existing arc and polygon layers. The offshore boundaries are currently being reviewed by the legal counsels of the  Massachusetts Highway Department and  NOAA as well as the Federal Baseline Committee. This data will not be distributed until the termination points of the offshore boundaries are approved by the Federal  Baseline Committee and the Massachusetts Legislature.

This datalayer, except the coastline, was created by MassGIS. Boundaries for each community were created by adjusting the existing 1:25,000 scale boundaries to connect the survey points (TOWNSSURVEY_PT) of a community. In many areas, the boundary creation was simply a matter of "connecting the dots" from one boundary point to the next. Where boundaries follow a stream/river or road right-of-way (ROW) the boundary was approximately delineated using the 2001 Half Meter Color Orthophotography as a base. All boundaries that follow a water body or a ROW are coded in the attribute table in the BND_QUAL field.

A complex boundary situation occurs when a survey point is a "witness mark", denoted by the letters WM in the coordinate name. A witness mark point is an "on-land" representation of the next point along the boundary when that next point is in a river, wetland, or pond. A line drawn between the point before a witness mark and a witness mark point gives you the direction of the town boundary as it proceeds to the next point in the river, wetland, or pond. Witness marks are often but not always on the town boundary. The Harbor and Land Commission Town Boundary Atlases included large-scale maps of individual boundary point locations. Digital images of these maps taken by MassGIS were also used as a guide in creating the town boundaries layer.

The source for the coastal boundary was the DEP Wetlands (1:12,000) data layer, with the boundary being the upland-side boundaries of tidal flats and rocky inter-tidal zones. The coastline boundary was then appended to the town boundary (TOWNSSURVEY_ARC). The polygon layer (TOWNSSURVEY_POLY) was generated from TOWNSSURVEY_ARC and label points using ArcGIS software.

The TOWNSSURVEY_POLYM layer was created by dissolving the TOWNSSURVEY_POLY feature class; a subset of the attribute table was retained, and the AREA and SQUARE_MILES fields were calculated for the entirety of each town.

Items in TOWNSSURVEY_POLY:

Item Name		Width		Type		Contents
TOWN		21		c		City or town name
TOWN-ID		3		I		MassGIS Town-ID Code (1-351)
POP1980		6		I		US Census Town Population: 1980
POP1990		6		I		US Census Town Population: 1990
POP2000		6		I		US Census Town Population: 2000
POPCH80_90		5		I		Population change, 1980-1990
POPCH90_00		5		I		Population change, 1990-2000
TYPE		2		C		C = City, T = Town, TC = Town with City form of government
ISLAND		1		I		Polygon is (1) / is NOT (0) an island - many towns are composed of many polygons
COASTAL_POLY		3		C		YES = Ocean or water polygon, within municipal limits NO = Land polygon
FOURCOLOR		1		I		Codes (1,2,3,4) allowing shading of all towns using 4 symbols (based on four-color theorem, where no adjacent polygons have same symbol)
FIPS_STCO		5		I		Federal Information Processing Standard (FIPS) State/County Code
CCD_MCD		3		C		US Census Town Code
FIPS_PLACE		5		C		Federal Information Processing Standard (FIPS) Town Code
FIPS_MCD		8		I		FIPS State & County & Census Town Code concatenated
FIPS_COUNTY		3		I		FIPS County only code
ACRES		10,3		F		Area in Acres
SQUARE_MILES		8,3		F		Area in Square Miles

The ArcGIS-added SHAPE_AREA field stores the polygon area in square meters; SHAPE_LEN is the polygon perimeter in meters.

Items in TOWNSSURVEY_ARC:

Item Name		Width		Type		Contents
BND_QUAL		1		I		Boundary Quality: 1 = Straight connect from one boundary point to another 2 = Boundary line follows a right of way (ROW)  which was digitized from the apparent edge of ROW visible on the 2001 color orthophotos 3 = boundary line follows a river or stream center 4 = boundary line falls within the Quabin Reservior 5 = boundary line falls within the coastline 6 = boundary line follows a property parcel 7 = Boundary line follows a right of way (ROW) which was snapped to linework in digital ROW plan data provided by municipality
FINISHED		3		C		YES = the boundary line has been adjusted from the 1:25,000 scale boundary layer NO = the boundary line has not been adjusted from the 1:25,000 scale boundary layer
BND_UNCLAS		1		I		Unclassified (Unfinished) Boundaries: 0 = boundary line is either part of the new imported coastline or was updated 1 = boundary line was not updated because a ROW map is needed 2 = boundary line was not updated because the river/stream is not visible in imagery 3 = boundary line was not updated due to some other reason
REASON		30		C		Not Applicable = boundary line is either part of the new imported coastline or was updated ROW map needed = boundary line was not updated because a ROW map is needed River/stream not visible = boundary line was not updated because the river/stream is not visible in imagery Other problem = boundary line was not updated due to some other reason
OUTLINE		2		I		1 = Interstate Boundary 4 = Coastline 17 = Internal Boundary

The ArcGIS-added field SHAPE_LEN is the line's length in meters.

Items in TOWNSSURVEY_POINT:

Item Name		Width		Type		Contents
CORNER		100		C		Survey point corner name
ID1		4		I		Sequential unique whole numbers that are automatically generated while the data was in Microsoft Access
NORTH83		10,3		F		Northing coordinate in NAD83 meters
EAST83		10,3		F		Easting coordinate in NAD83 meters
USE		3		C		YES = survey coordinate should be used in boundary delineation NO = survey coordinate should not be used in boundary delineation

See the older Community Boundaries (Towns) layer for files that may be joined to TOWNSSURVEY_POLY to display additional information at the municipal level.

To display just the "land area" of each town, use the definition query of COASTAL_POLY = 'NO' for the TOWNSSURVEY_POLY layer (this query is used in the themes in the MassGIS Data Viewer). For the TOWNSSURVEY_ARC layer, symbolizing on the OUTLINE field will allow for the display of coastline as well as inter-municipal boundaries in the water, where available. See the second image above for an example.

MassGIS maintains this datalayer. Future updates are described in the "Overview" section above. If you have questions or comments about these layers please contact MassGIS.

The TOWNSSURVEY_POLYM layer was added in May, 2006. At the same time, the TOWNS_ID field was dropped. Joins to the table on town number should be based on TOWN_ID.

Boundaries were modified in November and December, 2007, in five locations in Norfolk County, adjusted to match surveyed right-of-way (ROW) plans provided by the Norfolk County Engineering department. Edits to the ARC, POLY and POLYM layers included:

 - Bay Road (Sharon-Stoughton);
 - Clapboardtree Street (Norwood-Westwood);
 - Old Post Road (Walpole-Sharon);
 - Canton Street (Norwood-Westwood and Canton-N-W);
 - County Street (Dover-Walpole between Medfield and Westwood)

Also see the Community Boundaries (Towns) datalayer.

Last Updated 4/11/2008
EOEA Disclaimer | Privacy Policy