ZIP code 01863: Chelmsford, MA
ZIP code 01863 is in Middlesex County, Massachusetts, outside any city or Census-designated place. It is in Massachusetts's 3rd congressional district. Its state senate district is Third Middlesex District; its state house districts are 16th Middlesex District (85%) and 2nd Middlesex District (15%).
See it on the mapAll of Massachusetts
City and county
Outside any city or Census-designated place.
| County | Share of ZIP residents |
|---|---|
| Middlesex County | 100% |
| Town or county subdivision | Share of ZIP residents |
|---|---|
| Chelmsford town | 100% |
Congressional district
| Congressional district | Share of ZIP residents |
|---|---|
| Massachusetts's 3rd congressional district (MA-03) | 100% |
Elected officials
| Office | Member | Contact | Share of residents |
|---|---|---|---|
| U.S. Representative (MA-03) | Lori Trahan (D) | 202-225-3411 | 100% |
| U.S. Senator | Edward J. Markey (D) | 202-224-2742 · contact form | statewide |
| U.S. Senator | Elizabeth Warren (D) | 202-224-4543 · contact form | statewide |
| State Senator (Third Middlesex District) | Mike Barrett (Democratic) | 100% | |
| State Representative (2nd Middlesex District) | Jim Arciero (Democratic) | 15% |
Officials serving now (members of Congress until January 3, 2027). Sources: State legislators: Open States (public domain); Members of Congress: the @unitedstates project, congress-legislators (CC0).
Local government
- Middlesex County laws: search for the Middlesex County, Massachusetts code of ordinances
State legislative districts
| State senate district | Share of ZIP residents |
|---|---|
| Third Middlesex District | 100% |
| State house district | Share of ZIP residents |
|---|---|
| 16th Middlesex District | 85% |
| 2nd Middlesex District | 15% |
Voting precincts
4 voting precincts overlap ZIP 01863. Map them, with each precinct's share of the ZIP's residents.
Get this in your AI agent
Your agent can get these cities, counties, districts and precincts with their shares, and their GeoJSON boundaries, from Boundary Atlas. Add https://atlas-production-d344.up.railway.app/mcp to Claude, ChatGPT, Cursor or Codex (free, no key; how), then:
related_geographies(id="us:zcta:01863")
ZIP 01863 here is the Census Bureau's ZIP Code Tabulation Area, which approximates the USPS ZIP Code; PO-box-only ZIPs have none. Districts are the maps in force for the November 3, 2026 election.