ZIP Code 51566 — Red Oak, IA
51566 is a standard (street delivery) ZIP code serving Red Oak, Iowa, in Montgomery 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 51566 at a glance
| ZIP code | 51566 |
|---|---|
| Primary city | Red Oak |
| State | Iowa (IA) |
| County | Montgomery FIPS 19137 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Chicago |
| Population | 7,010 |
| Coordinates | 41.015100, -95.229940 |
How ZIP+4 works in 51566
The four digits after the hyphen encode a delivery segment inside 51566. 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 51566 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 51566.
| ZIP | City | Distance |
|---|---|---|
| 51573 | Stanton, IA | 7.5 mi |
| 51533 | Emerson, IA | 7.9 mi |
| 51532 | Elliott, IA | 10.3 mi |
| 51638 | Essex, IA | 12.3 mi |
| 51541 | Henderson, IA | 12.8 mi |
| 50864 | Villisca, IA | 13.3 mi |
| 51645 | Imogene, IA | 13.6 mi |
| 51540 | Hastings, IA | 14 mi |
| 51535 | Griswold, IA | 15.4 mi |
| 50847 | Grant, IA | 15.5 mi |
| 51549 | Macedonia, IA | 16.4 mi |
| 51525 | Carson, IA | 18.1 mi |
Questions about 51566
What is the ZIP+4 code for 51566?
51566 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 51566, you need to look up a specific street address to get them.
What city is 51566?
51566 is assigned to Red Oak, Iowa, in Montgomery 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.