Boundary Atlas

ZIP code 08558: Montgomery, NJ

ZIP code 08558 is in Blawenburg (3.7% of residents) and Skillman (3.1%), in Somerset County (99%) and Mercer County (0.9%), New Jersey. 93% of its residents live outside city limits. It is in New Jersey's 12th congressional district. Its state senate districts are State Senate District 16 (99%) and State Senate District 15 (0.9%); its state house districts are Assembly District 16 (99%) and Assembly District 15 (0.9%).

7,754residents (2020 Census)
15.6 sq miland area
2cities and towns
1congressional district
10voting precincts

See it on the mapAll of New Jersey

City and county

City or townShare of ZIP residents
Blawenburg3.7%
Skillman3.1%

CountyShare of ZIP residents
Somerset County99%
Mercer County0.9%

Town or county subdivisionShare of ZIP residents
Montgomery township99%
Hopewell township0.9%

Congressional district

Congressional districtShare of ZIP residents
New Jersey's 12th congressional district (NJ-12)100%

State legislative districts

State senate districtShare of ZIP residents
State Senate District 1699%
State Senate District 150.9%

State house districtShare of ZIP residents
Assembly District 1699%
Assembly District 150.9%

Voting precincts

10 voting precincts overlap ZIP 08558. 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:08558")

ZIP 08558 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.