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MassGIS Data: Massachusetts Senate Legislative Districts (2021)

January 2023

The Senate Legislative Districts datalayer reflects the state senate voting district boundaries for Massachusetts that went into effect beginning with the 2022 elections. Voting resources can be found on the Secretary of the Commonwealth’s website.

Table of Contents


.zip file (3.5 MB), with ESRI Shapefiles (arc and polygon) and ArcMap layer file (.lyr)


Staff at the Massachusetts General Court Special Joint Committee on Redistricting developed this layer. Governor Baker signed the 40 districts into law on November 4, 2021, with Chapter 82 of the Acts of 2021.

The name of the statewide datalayers are SENATE2021_POLY (polygons) and SENATE2021_ARC (linear features).


MassGIS downloaded the data from the Joint Committee on Redistricting website and incorporated a coastline into the polygons using 2020 TIGER/Line "faces" data downloaded from the U.S. Census Bureau. MassGIS converted the polygons to linear features to produce the _ARC feature class and added attributes to both feature classes.

The data layers are based upon 2020 U.S. Census geography and therefore will not perfectly align to MassGIS's Municipalities layer (nor any others based on it).


The SENATE2021_POLY attribute table has the following fields:

Field Name Width / Type Description
SENDISTNUM 5 / I Senate District number
SEN_DIST 43 / C Name of Senate District
SEN_FIRST 13 / C First name of Senator
SEN_LAST 15 / C Last name of Senator
SEN_PARTY 3 / C Senator's political party
SENATOR 40 / C Senator's full name and party
URL 150 / C Senator's Web site address


In the SENATE2021_ARC attribute table, the field OUTLINE is coded as follows:

  • 0 = Internal district boundaries
  • 1 = State
  • 2 = Coastline


MassGIS maintains the layer and will make updates as needed.

Member names from the results of the November 2022 election were entered in January 2023. Coastal boundaries were updated at the same time.

Also see the 2021 House data layer.

Additional information, file formats, and PDF maps can be found on the Joint Committee on Redistricting website.

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