ZIP Code 57730 — Custer, SD
57730 is a standard (street delivery) ZIP code serving Custer, South Dakota, 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 57730 at a glance
| ZIP code | 57730 |
|---|---|
| Primary city | Custer |
| State | South Dakota (SD) |
| County | Custer FIPS 46033 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Denver |
| Population | 5,596 |
| Coordinates | 43.725610, -103.637330 |
How ZIP+4 works in 57730
The four digits after the hyphen encode a delivery segment inside 57730. 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 57730 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 57730.
| ZIP | City | Distance |
|---|---|---|
| 57773 | Pringle, SD | 9.3 mi |
| 57751 | Keystone, SD | 14.5 mi |
| 57745 | Hill City, SD | 21.2 mi |
| 57747 | Hot Springs, SD | 24.5 mi |
| 57702 | Rapid City, SD | 24.6 mi |
| 57738 | Fairburn, SD | 25.7 mi |
| 57735 | Edgemont, SD | 31.9 mi |
| 57766 | Oral, SD | 34 mi |
| 57718 | Black Hawk, SD | 34.1 mi |
| 57759 | Nemo, SD | 34.4 mi |
| 57701 | Rapid City, SD | 34.7 mi |
| 57703 | Rapid City, SD | 35.2 mi |
Questions about 57730
What is the ZIP+4 code for 57730?
57730 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 57730, you need to look up a specific street address to get them.
What city is 57730?
57730 is assigned to Custer, South Dakota, 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.