ZIP Code 57440 — Frankfort, SD
57440 is a standard (street delivery) ZIP code serving Frankfort, South Dakota, in Spink 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 57440 at a glance
| ZIP code | 57440 |
|---|---|
| Primary city | Frankfort |
| State | South Dakota (SD) |
| County | Spink FIPS 46115 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Chicago |
| Population | 466 |
| Coordinates | 44.850200, -98.259560 |
How ZIP+4 works in 57440
The four digits after the hyphen encode a delivery segment inside 57440. 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 57440 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 57440.
| ZIP | City | Distance |
|---|---|---|
| 57436 | Doland, SD | 8.2 mi |
| 57477 | Turton, SD | 13.7 mi |
| 57469 | Redfield, SD | 15.5 mi |
| 57348 | Hitchcock, SD | 16.6 mi |
| 57258 | Raymond, SD | 16.6 mi |
| 57424 | Ashton, SD | 17.7 mi |
| 57476 | Tulare, SD | 20.1 mi |
| 57322 | Carpenter, SD | 20.8 mi |
| 57429 | Brentford, SD | 21.5 mi |
| 57461 | Mellette, SD | 23.1 mi |
| 57434 | Conde, SD | 23.7 mi |
| 57225 | Clark, SD | 26.2 mi |
Questions about 57440
What is the ZIP+4 code for 57440?
57440 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 57440, you need to look up a specific street address to get them.
What city is 57440?
57440 is assigned to Frankfort, South Dakota, in Spink 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.