ZIP Code 94503 — American Canyon, CA
94503 is a standard (street delivery) ZIP code serving American Canyon, California, in Napa 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 94503 at a glance
| ZIP code | 94503 |
|---|---|
| Primary city | American Canyon |
| State | California (CA) |
| County | Napa FIPS 06055 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Los_Angeles |
| Population | 21,841 |
| Coordinates | 38.194540, -122.230420 |
How ZIP+4 works in 94503
The four digits after the hyphen encode a delivery segment inside 94503. 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 94503 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 94503.
| ZIP | City | Distance |
|---|---|---|
| 94589 | Vallejo, CA | 3.7 mi |
| 94591 | Vallejo, CA | 5 mi |
| 94559 | Napa, CA | 5.3 mi |
| 94534 | Fairfield, CA | 6.7 mi |
| 94592 | Vallejo, CA | 6.8 mi |
| 94590 | Vallejo, CA | 6.9 mi |
| 94510 | Benicia, CA | 8.6 mi |
| 94525 | Crockett, CA | 10.1 mi |
| 94569 | Port Costa, CA | 10.6 mi |
| 94572 | Rodeo, CA | 11.8 mi |
| 94547 | Hercules, CA | 13.1 mi |
| 95476 | Sonoma, CA | 13.2 mi |
Questions about 94503
What is the ZIP+4 code for 94503?
94503 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 94503, you need to look up a specific street address to get them.
What city is 94503?
94503 is assigned to American Canyon, California, in Napa 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.