ZIP Code 83251 — Mackay, ID
83251 is a standard (street delivery) ZIP code serving Mackay, Idaho, in Custer 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 83251 at a glance
| ZIP code | 83251 |
|---|---|
| Primary city | Mackay |
| State | Idaho (ID) |
| County | Custer FIPS 16037 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Boise |
| Population | 1,443 |
| Coordinates | 43.907380, -113.864250 |
How ZIP+4 works in 83251
The four digits after the hyphen encode a delivery segment inside 83251. 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 83251 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 83251.
| ZIP | City | Distance |
|---|---|---|
| 83255 | Moore, ID | 23.7 mi |
| 83353 | Sun Valley, ID | 27.9 mi |
| 83354 | Sun Valley, ID | 28 mi |
| 83333 | Hailey, ID | 29 mi |
| 83213 | Arco, ID | 35.1 mi |
Questions about 83251
What is the ZIP+4 code for 83251?
83251 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 83251, you need to look up a specific street address to get them.
What city is 83251?
83251 is assigned to Mackay, Idaho, in Custer 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.