ZIP Code 94509 — Antioch, CA
94509 is a standard (street delivery) ZIP code serving Antioch, California, in Contra Costa 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 94509 at a glance
| ZIP code | 94509 |
|---|---|
| Primary city | Antioch |
| State | California (CA) |
| County | Contra Costa FIPS 06013 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Los_Angeles |
| Population | 70,090 |
| Coordinates | 37.992140, -121.814200 |
How ZIP+4 works in 94509
The four digits after the hyphen encode a delivery segment inside 94509. 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 94509 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 Antioch
Nearby ZIP codes
Showing the closest twelve. See every ZIP code within 25 miles of 94509.
| ZIP | City | Distance |
|---|---|---|
| 94531 | Antioch, CA | 3.1 mi |
| 94565 | Pittsburg, CA | 6.3 mi |
| 94561 | Oakley, CA | 6.7 mi |
| 94517 | Clayton, CA | 7.8 mi |
| 94513 | Brentwood, CA | 8.4 mi |
| 94521 | Concord, CA | 8.9 mi |
| 94548 | Knightsen, CA | 8.9 mi |
| 94512 | Birds Landing, CA | 9.3 mi |
| 94511 | Bethel Island, CA | 9.8 mi |
| 94519 | Concord, CA | 10.8 mi |
| 94598 | Walnut Creek, CA | 11.5 mi |
| 94518 | Concord, CA | 11.7 mi |
Questions about 94509
What is the ZIP+4 code for 94509?
94509 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 94509, you need to look up a specific street address to get them.
What city is 94509?
94509 is assigned to Antioch, California, in Contra Costa 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.