ZIP Code 90603 — Whittier, CA
90603 is a standard (street delivery) ZIP code serving Whittier, 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 90603 at a glance
| ZIP code | 90603 |
|---|---|
| Primary city | Whittier |
| State | California (CA) |
| County | Los Angeles FIPS 06037 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Los_Angeles |
| Population | 21,118 |
| Coordinates | 33.944870, -117.992390 |
How ZIP+4 works in 90603
The four digits after the hyphen encode a delivery segment inside 90603. 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 90603 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.
Other ZIP codes in Whittier
Nearby ZIP codes
Showing the closest twelve. See every ZIP code within 25 miles of 90603.
| ZIP | City | Distance |
|---|---|---|
| 90604 | Whittier, CA | 1.5 mi |
| 90605 | Whittier, CA | 1.7 mi |
| 90631 | La Habra, CA | 2.4 mi |
| 90602 | Whittier, CA | 2.6 mi |
| 90639 | La Mirada, CA | 3 mi |
| 90638 | La Mirada, CA | 3.1 mi |
| 91745 | Hacienda Heights, CA | 3.9 mi |
| 90670 | Santa Fe Springs, CA | 4.1 mi |
| 92833 | Fullerton, CA | 4.8 mi |
| 90606 | Whittier, CA | 4.8 mi |
| 90601 | Whittier, CA | 4.9 mi |
| 90621 | Buena Park, CA | 4.9 mi |
Questions about 90603
What is the ZIP+4 code for 90603?
90603 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 90603, you need to look up a specific street address to get them.
What city is 90603?
90603 is assigned to Whittier, 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.