ZIP Code 51521 — Avoca, IA
51521 is a standard (street delivery) ZIP code serving Avoca, Iowa, in Pottawattamie 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 51521 at a glance
| ZIP code | 51521 |
|---|---|
| Primary city | Avoca |
| State | Iowa (IA) |
| County | Pottawattamie FIPS 19155 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Chicago |
| Population | 1,953 |
| Coordinates | 41.479870, -95.345260 |
How ZIP+4 works in 51521
The four digits after the hyphen encode a delivery segment inside 51521. 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 51521 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 51521.
| ZIP | City | Distance |
|---|---|---|
| 51570 | Shelby, IA | 6.6 mi |
| 51536 | Hancock, IA | 6.7 mi |
| 51577 | Walnut, IA | 7.4 mi |
| 51553 | Minden, IA | 11.3 mi |
| 51560 | Oakland, IA | 11.5 mi |
| 51537 | Harlan, IA | 11.8 mi |
| 51552 | Marne, IA | 11.9 mi |
| 51563 | Persia, IA | 14.5 mi |
| 51565 | Portsmouth, IA | 14.7 mi |
| 51531 | Elk Horn, IA | 15.2 mi |
| 51559 | Neola, IA | 16.4 mi |
| 51544 | Lewis, IA | 16.8 mi |
Questions about 51521
What is the ZIP+4 code for 51521?
51521 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 51521, you need to look up a specific street address to get them.
What city is 51521?
51521 is assigned to Avoca, Iowa, in Pottawattamie 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.