ZIP code 94509: Antioch, CA
ZIP code 94509 is in Antioch, in Contra Costa County, California. It is in California's 9th congressional district. Its state senate districts are State Senate District 9 (100%) and State Senate District 3 (<0.1%); its state house district is Assembly District 15.
See it on the mapAll of California
City and county
| City or town | Share of ZIP residents |
|---|---|
| Antioch | 100% |
| County | Share of ZIP residents |
|---|---|
| Contra Costa County | 100% |
| Town or county subdivision | Share of ZIP residents |
|---|---|
| Antioch-Pittsburg CCD | 93% |
| Tassajara CCD | 7.3% |
Congressional district
| Congressional district | Share of ZIP residents |
|---|---|
| California's 9th congressional district (CA-09) | 100% |
| California's 10th congressional district (CA-10) | land only |
Elected officials
| Office | Member | Contact | Share of residents |
|---|---|---|---|
| U.S. Representative (CA-09) | Josh Harder (D) | 202-225-4540 | 100% |
| U.S. Representative (CA-10) | Mark DeSaulnier (D) | 202-225-2095 | <0.1% |
| U.S. Senator | Adam B. Schiff (D) | 202-224-3841 | statewide |
| U.S. Senator | Alex Padilla (D) | 202-224-3553 · contact form | statewide |
| State Senator (State Senate District 9) | Tim Grayson (Democratic) | 925-258-1176 | 100% |
| State Senator (State Senate District 3) | Christopher Cabaldon (Democratic) | 707-454-3808 | <0.1% |
| Assembly Member (Assembly District 15) | Anamarie Avila Farias (Democratic) | 925-521-1511 | 100% |
Elected in 2024 under CA's previous congressional map; this district's lines changed for the 120th Congress (seated January 3, 2027).
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
- Antioch website: https://www.antiochca.gov/
- Antioch laws: search for the Antioch, California code of ordinances
- Contra Costa County website: https://www.contracosta.ca.gov/
- Contra Costa County laws: search for the Contra Costa County, California code of ordinances
State legislative districts
| State senate district | Share of ZIP residents |
|---|---|
| State Senate District 9 | 100% |
| State Senate District 3 | <0.1% |
| State house district | Share of ZIP residents |
|---|---|
| Assembly District 15 | 100% |
Voting precincts
42 voting precincts overlap ZIP 94509. 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:94509")
ZIP 94509 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.