ZIP code 80403: Fairmount, CO
ZIP code 80403 is in Fairmount (32% of residents), Golden (25%), Arvada (13%) and Coal Creek (12%), in Jefferson County (94%), Boulder County (3.7%) and Gilpin County (2.4%), Colorado. 18% of its residents live outside city limits. It is in Colorado's 7th congressional district (85%) and Colorado's 2nd congressional district (15%). Its state senate districts are State Senate District 20 (55%), State Senate District 22 (25%), State Senate District 19 (13%), State Senate District 15 (3.7%) and State Senate District 8 (2.4%); its state house districts are State House District 27 (48%), State House District 24 (46%) and State House District 49 (6.1%).
See it on the mapAll of Colorado
City and county
| City or town | Share of ZIP residents |
|---|---|
| Fairmount | 32% |
| Golden | 25% |
| Arvada | 13% |
| Coal Creek | 12% |
| County | Share of ZIP residents |
|---|---|
| Jefferson County | 94% |
| Boulder County | 3.7% |
| Gilpin County | 2.4% |
| Town or county subdivision | Share of ZIP residents |
|---|---|
| Golden CCD | 80% |
| Northeast Jefferson CCD | 14% |
| Bald Mountain CCD | 3.7% |
| Central City CCD | 2.4% |
Congressional districts
| Congressional district | Share of ZIP residents |
|---|---|
| Colorado's 7th congressional district (CO-07) | 85% |
| Colorado's 2nd congressional district (CO-02) | 15% |
This ZIP is split between districts. A mailing address in it could be in either; the map or locate_point gives the district for an exact address.
State legislative districts
| State senate district | Share of ZIP residents |
|---|---|
| State Senate District 20 | 55% |
| State Senate District 22 | 25% |
| State Senate District 19 | 13% |
| State Senate District 15 | 3.7% |
| State Senate District 8 | 2.4% |
| State house district | Share of ZIP residents |
|---|---|
| State House District 27 | 48% |
| State House District 24 | 46% |
| State House District 49 | 6.1% |
Voting precincts
20 voting precincts overlap ZIP 80403. 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:80403")
ZIP 80403 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.