Boundary Atlas

ZIP code 07856: Mount Arlington, NJ

ZIP code 07856 is in Mount Arlington (98% of residents), in Morris County, New Jersey. It is in New Jersey's 7th congressional district. Its state senate districts are State Senate District 25 (98%) and State Senate District 24 (1.6%); its state house districts are Assembly District 25 (98%) and Assembly District 24 (1.6%).

4,791residents (2020 Census)
3.4 sq miland area
1cities and towns
1congressional district
5voting precincts

See it on the mapAll of New Jersey

City and county

City or townShare of ZIP residents
Mount Arlington98%

CountyShare of ZIP residents
Morris County100%

Town or county subdivisionShare of ZIP residents
Mount Arlington borough98%
Roxbury township1.6%

Congressional district

Congressional districtShare of ZIP residents
New Jersey's 7th congressional district (NJ-07)100%

State legislative districts

State senate districtShare of ZIP residents
State Senate District 2598%
State Senate District 241.6%

State house districtShare of ZIP residents
Assembly District 2598%
Assembly District 241.6%

Voting precincts

5 voting precincts overlap ZIP 07856. 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:07856")

ZIP 07856 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.