ZIP code 91789: Walnut, CA
ZIP code 91789 is in Walnut (69% of residents), Diamond Bar (21%), Rowland Heights (8.5%) and Pomona (1.6%), in Los Angeles County, California. It is in California's 31st congressional district (71%) and California's 38th congressional district (29%). Its state senate districts are State Senate District 30 (98%) and State Senate District 22 (1.6%); its state house districts are Assembly District 56 (98%) and Assembly District 53 (1.6%).
See it on the mapAll of California
City and county
| City or town | Share of ZIP residents |
|---|---|
| Walnut | 69% |
| Diamond Bar | 21% |
| Rowland Heights | 8.5% |
| Pomona | 1.6% |
| County | Share of ZIP residents |
|---|---|
| Los Angeles County | 100% |
| Town or county subdivision | Share of ZIP residents |
|---|---|
| East San Gabriel Valley CCD | 100% |
Congressional districts
| Congressional district | Share of ZIP residents |
|---|---|
| California's 31st congressional district (CA-31) | 71% |
| California's 38th congressional district (CA-38) | 29% |
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.
Elected officials
| Office | Member | Contact | Share of residents |
|---|---|---|---|
| U.S. Representative (CA-31) | Gilbert Ray Cisneros, Jr. (D) | 202-225-5256 | 71% |
| U.S. Representative (CA-38) | Linda T. Sánchez (D) | 202-225-6676 | 29% |
| 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 30) | Bob Archuleta (Democratic) | 562-406-1001 | 98% |
| State Senator (State Senate District 22) | Susan Rubio (Democratic) | 909-460-6064 | 1.6% |
| Assembly Member (Assembly District 56) | Lisa Calderon (Democratic) | 562-692-5858 | 98% |
| Assembly Member (Assembly District 53) | Michelle Rodriguez (Democratic) | 909-902-9606 | 1.6% |
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
- Walnut website: http://www.cityofwalnut.org/
- Walnut laws: search for the Walnut, California code of ordinances
- Diamond Bar laws: search for the Diamond Bar, California code of ordinances
- Rowland Heights website: http://www.rowland-heights.org/
- Rowland Heights laws: search for the Rowland Heights, California code of ordinances
- Los Angeles County website: https://lacounty.gov
- Los Angeles County laws: search for the Los Angeles County, California code of ordinances
State legislative districts
| State senate district | Share of ZIP residents |
|---|---|
| State Senate District 30 | 98% |
| State Senate District 22 | 1.6% |
| State house district | Share of ZIP residents |
|---|---|
| Assembly District 56 | 98% |
| Assembly District 53 | 1.6% |
Voting precincts
17 voting precincts overlap ZIP 91789. 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:91789")
ZIP 91789 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.