ZIP Code 91770 — Rosemead, CA
91770 is a standard (street delivery) ZIP code serving Rosemead, California, in Los Angeles County. To mail something here you only need these five digits — but the four-digit extension narrows delivery to a single point, and it is what USPS bulk postage discounts are priced on.
ZIP code 91770 at a glance
| ZIP code | 91770 |
|---|---|
| Primary city | Rosemead |
| State | California (CA) |
| County | Los Angeles FIPS 06037 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Los_Angeles |
| Population | 58,382 |
| Coordinates | 34.063950, -118.083610 |
How ZIP+4 works in 91770
The four digits after the hyphen encode a delivery segment inside 91770. In practice one segment usually means:
- One side of one block — odd numbers on a street between two cross streets
- A single large building, or one floor of it
- A group of PO boxes, sometimes a single box
- A single business that receives enough mail to warrant its own code
That is why 91770 has no single ZIP+4: two neighbors across the street from each other usually have different ones. Enter a street address above and we will return the exact nine-digit code along with the standardized USPS address format.
Nearby ZIP codes
Showing the closest twelve. See every ZIP code within 25 miles of 91770.
| ZIP | City | Distance |
|---|---|---|
| 91776 | San Gabriel, CA | 1.9 mi |
| 91755 | Monterey Park, CA | 2.1 mi |
| 91733 | South El Monte, CA | 2.2 mi |
| 91731 | El Monte, CA | 2.7 mi |
| 91780 | Temple City, CA | 3 mi |
| 91801 | Alhambra, CA | 3.1 mi |
| 91775 | San Gabriel, CA | 3.5 mi |
| 91754 | Monterey Park, CA | 3.6 mi |
| 91803 | Alhambra, CA | 3.7 mi |
| 90640 | Montebello, CA | 3.7 mi |
| 91732 | El Monte, CA | 4 mi |
| 91108 | San Marino, CA | 4.4 mi |
Questions about 91770
What is the ZIP+4 code for 91770?
91770 is the five-digit ZIP code. The ZIP+4 adds four more digits that identify a specific delivery point — usually one side of a city block, a single building, or a group of PO boxes. Because those four digits change from address to address within 91770, you need to look up a specific street address to get them.
What city is 91770?
91770 is assigned to Rosemead, California, in Los Angeles County.
Do I need to use the ZIP+4?
It is optional for ordinary mail, but it speeds up sorting and it is required for most USPS bulk-mail postage discounts. Many address-verification and e-commerce systems also use ZIP+4 to confirm a delivery point exists.
Need thousands of these?
Upload a CSV and get ZIP+4, county, carrier route, and delivery-point data appended to every row — or call the API directly.