| City: | South Pasadena, California |
| City Alias: | S Pasadena |
| County: | Los Angeles County |
| Timezone: | Pacific (GMT -08:00) |
| Local Time: | 9:35:20 AM |
| Population: | No Population Data |
| Area Codes: | 323 / 626 / 738 |
| Classification: | PO Box |
| Coordinates: | 34.1162, -118.1497 |
| Quick Link: |
South Pasadena maintains two ZIP codes. 91030 handles street delivery across the city, while 91031 exists solely for PO Box service at the local post office. This isn't a separate community. It's a postal accounting distinction that lets USPS track PO Box operations independently from carrier routes.
The 91031 ZIP has no geographic territory of its own. It's a point location contained within 91030's boundaries. All 1,026 PO Boxes served by this ZIP sit at the South Pasadena post office on Fremont Avenue. The 143 ZIP+4 records associated with Fremont Ave aren't street addresses. They're PO Box Street Addressing records that let customers receive packages using the post office's physical address instead of a traditional PO Box number.
With 488 business delivery points and 1,026 PO Boxes, local businesses use PO Box service heavily. Some prefer a PO Box for privacy or consistency. Others use it because they don't have a physical storefront. The post office sits in a walkable commercial district, making it convenient for downtown merchants to pick up mail.
South Pasadena is a small, affluent city of about 26,000 residents surrounded by Pasadena, Los Angeles, and San Marino. It's known for historic homes, a traditional downtown, and resistance to freeway construction that preserved its residential character. Residents who want a PO Box use 91031. Everyone else receives mail at their street address via 91030.
The only street is Fremont Avenue, the post office location. These records are PO Box Street Addressing, not traditional street delivery.
ZIP Code 91031 supports both business and residential activity. According to the Business Census (2024), there are 12 business establishments, employing about 53 people with an annual payroll of $2,892,000.
| # Residential Mailboxes: | 0Source: USPS |
| # Business Mailboxes: | 0Source: USPS |
| Total Delivery Receptacles: | 1,691Source: USPS |
| Single Family Delivery Units: | 0Source: USPS |
| Multi Family Delivery Units: | 0Source: USPS |
| # of Businesses: | 12Source: CBP |
| 1st Quarter Payroll: | $861,000Source: CBP |
| Annual Payroll: | $2,892,000Source: CBP |
| # of Employees: | 53Source: CBP |
ZIP Code 91031 is located in Los Angeles County, California, within the Los Angeles-Long Beach-Anaheim, CA Metropolitan Statistical Area (CBSA 31080) and California's 28th Congressional District. This Metro area has a population of 0 people, about 0.00% of whom live in ZIP Code 91031, and is subdivided into the Los Angeles-Long Beach-Glendale, CA division. It covers 0 sq mi of land and a water area of 0 sq mi.
| CBSA Name: | Los Angeles-Long Beach-Anaheim, CASource: Census |
| CBSA Number: | 31080Source: Census |
| CBSA Type: | MetroSource: Census |
| CBSA Division: | Los Angeles-Long Beach-Glendale, CA (CBSA Div 31084)Source: Census |
| CBSA Population: | 0Source: Census |
| MSA: | Los Angeles-Riverside-Orange County, CASource: Census |
| Land Area: | --Source: Census |
| Water Area: | --Source: Census |
| Congressional District: | 28Source: USPS |
| Congressional Land Area: | 218.45 sq miSource: Census |
| PMSA: | Los Angeles-Long Beach, CA PMSASource: Census |
| Intro Date: | < 2004-10Source: ZIP-Codes.com |
| Place FIPS Code: | 0673220Source: Census |
| Place Name: | South Pasadena city; CaliforniaSource: Census |
We could not locate which school district 91031 belongs to, but we will update this once new district data is released. There are no public schools nor private schools with a mailing address in this ZIP Code. Listing Nearby schools instead. It also has 6 colleges, universities or post secondary education institutions nearby which would be a short commute to.
Our sources include trusted federal and licensed data from the United States Postal Service, U.S. Census Bureau, U.S. Geological Survey, Centers for Medicare & Medicaid Services, and the National Center for Education Statistics, along with proprietary datasets created by ZIP-Codes.com. Data last updated on February 1, 2026.