ZIP Code 57720 — Buffalo, SD
57720 is a standard (street delivery) ZIP code serving Buffalo, South Dakota, in Harding 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 57720 at a glance
| ZIP code | 57720 |
|---|---|
| Primary city | Buffalo |
| State | South Dakota (SD) |
| County | Harding FIPS 46063 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Denver |
| Population | 518 |
| Coordinates | 45.549700, -103.606550 |
How ZIP+4 works in 57720
The four digits after the hyphen encode a delivery segment inside 57720. 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 57720 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 57720.
| ZIP | City | Distance |
|---|---|---|
| 57776 | Redig, SD | 21.2 mi |
| 57755 | Ludlow, SD | 23.2 mi |
| 57724 | Camp Crook, SD | 23.4 mi |
| 57651 | Reva, SD | 26 mi |
| 59319 | Capitol, MT | 29.1 mi |
| 57650 | Ralph, SD | 34.1 mi |
Questions about 57720
What is the ZIP+4 code for 57720?
57720 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 57720, you need to look up a specific street address to get them.
What city is 57720?
57720 is assigned to Buffalo, South Dakota, in Harding 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.