ZIP Code 91384 — Castaic, CA
91384 is a standard (street delivery) ZIP code serving Castaic, 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 91384 at a glance
| ZIP code | 91384 |
|---|---|
| Primary city | Castaic |
| State | California (CA) |
| County | Los Angeles FIPS 06037 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Los_Angeles |
| Population | 26,478 |
| Coordinates | 34.516040, -118.672890 |
How ZIP+4 works in 91384
The four digits after the hyphen encode a delivery segment inside 91384. 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 91384 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 91384.
| ZIP | City | Distance |
|---|---|---|
| 91354 | Valencia, CA | 7.8 mi |
| 91355 | Valencia, CA | 8.1 mi |
| 91381 | Stevenson Ranch, CA | 10.4 mi |
| 91350 | Santa Clarita, CA | 11.3 mi |
| 91351 | Canyon Country, CA | 13.3 mi |
| 93532 | Lake Hughes, CA | 13.4 mi |
| 93015 | Fillmore, CA | 13.8 mi |
| 93063 | Simi Valley, CA | 14.3 mi |
| 91321 | Newhall, CA | 14.6 mi |
| 91390 | Santa Clarita, CA | 15.2 mi |
| 93040 | Piru, CA | 15.9 mi |
| 91311 | Chatsworth, CA | 16 mi |
Questions about 91384
What is the ZIP+4 code for 91384?
91384 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 91384, you need to look up a specific street address to get them.
What city is 91384?
91384 is assigned to Castaic, 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.