ZIP Code 83321 — Castleford, ID
83321 is a standard (street delivery) ZIP code serving Castleford, Idaho, in Twin Falls 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 83321 at a glance
| ZIP code | 83321 |
|---|---|
| Primary city | Castleford |
| State | Idaho (ID) |
| County | Twin Falls FIPS 16083 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Boise |
| Population | 482 |
| Coordinates | 42.359550, -114.863120 |
How ZIP+4 works in 83321
The four digits after the hyphen encode a delivery segment inside 83321. 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 83321 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 83321.
| ZIP | City | Distance |
|---|---|---|
| 83316 | Buhl, ID | 17.1 mi |
| 83301 | Twin Falls, ID | 17.6 mi |
| 83302 | Rogerson, ID | 18 mi |
| 83328 | Filer, ID | 19.2 mi |
| 83341 | Kimberly, ID | 25.6 mi |
| 83355 | Wendell, ID | 28.2 mi |
| 83334 | Hansen, ID | 29.5 mi |
| 83332 | Hagerman, ID | 30.4 mi |
| 89825 | Jackpot, NV | 32.4 mi |
| 83338 | Jerome, ID | 33.4 mi |
| 89826 | Jarbidge, NV | 40.7 mi |
Questions about 83321
What is the ZIP+4 code for 83321?
83321 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 83321, you need to look up a specific street address to get them.
What city is 83321?
83321 is assigned to Castleford, Idaho, in Twin Falls 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.