ZIP Code 91788 – Walnut, CA
Walnut, California · Los Angeles County · Pacific time
| ZIP code | 91788 |
|---|---|
| City | Walnut |
| State | California |
| County | Los Angeles County |
| Population | Not published (no Census ZIP area) |
| Time zone | Pacific · local time |
| ZIP type | PO box or unique ZIP (no Census area) |
| Center (lat, long) | 34.0203, -117.8653 |
Area codes in this area
These are the area codes that most often serve ZIP 91788 (including overlays). The exact area code depends on the phone number — landlines, mobiles and overlays can differ even on the same street.
Map
Nearby ZIP codes
About ZIP 91788
ZIP code 91788 is assigned to Walnut, California. It lies in Los Angeles County. It is a PO-box-only or single-address ZIP, so the Census Bureau does not publish an area for it; the location shown is approximate. The closest neighboring ZIP is 91789 (Walnut), about 0.6 miles away.
Every address in 91788 also has a 4-digit add-on code (ZIP+4) that points to a smaller delivery area. Use the box above to find it.
Sources: US Census Bureau (ZCTA, county relationship files), GeoNames (CC BY 4.0), NANPA via NumberResearch.org (CC BY 4.0). Map © OpenStreetMap contributors. ZIP areas are approximate. Population: U.S. Census Bureau, ACS 5-year estimates, 2024 (ZCTA). Data sources