ZIP Code 51545 — Little Sioux, IA
51545 is a standard (street delivery) ZIP code serving Little Sioux, Iowa, in Harrison 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 51545 at a glance
| ZIP code | 51545 |
|---|---|
| Primary city | Little Sioux |
| State | Iowa (IA) |
| County | Harrison FIPS 19085 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Chicago |
| Population | 267 |
| Coordinates | 41.838970, -96.020720 |
How ZIP+4 works in 51545
The four digits after the hyphen encode a delivery segment inside 51545. 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 51545 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 51545.
| ZIP | City | Distance |
|---|---|---|
| 51523 | Blencoe, IA | 5.7 mi |
| 51564 | Pisgah, IA | 6.1 mi |
| 51557 | Mondamin, IA | 7.6 mi |
| 51558 | Moorhead, IA | 9.3 mi |
| 68061 | Tekamah, NE | 10.2 mi |
| 51550 | Magnolia, IA | 12.6 mi |
| 51040 | Onawa, IA | 13.5 mi |
| 51556 | Modale, IA | 14.1 mi |
| 68020 | Decatur, NE | 15.4 mi |
| 51572 | Soldier, IA | 15.7 mi |
| 51579 | Woodbine, IA | 17.2 mi |
| 68029 | Herman, NE | 18 mi |
Questions about 51545
What is the ZIP+4 code for 51545?
51545 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 51545, you need to look up a specific street address to get them.
What city is 51545?
51545 is assigned to Little Sioux, Iowa, in Harrison 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.