ZIP Code 66521 — Onaga, KS
66521 is a standard (street delivery) ZIP code serving Onaga, Kansas, in Pottawatomie 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 66521 at a glance
| ZIP code | 66521 |
|---|---|
| Primary city | Onaga |
| State | Kansas (KS) |
| County | Pottawatomie FIPS 20149 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Chicago |
| Population | 1,417 |
| Coordinates | 39.476680, -96.221280 |
How ZIP+4 works in 66521
The four digits after the hyphen encode a delivery segment inside 66521. 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 66521 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 66521.
| ZIP | City | Distance |
|---|---|---|
| 66432 | Havensville, KS | 7.9 mi |
| 66549 | Westmoreland, KS | 11.6 mi |
| 66422 | Emmett, KS | 12.3 mi |
| 66540 | Soldier, KS | 13.2 mi |
| 66544 | Vermillion, KS | 14.9 mi |
| 66415 | Centralia, KS | 15.4 mi |
| 66417 | Corning, KS | 15.7 mi |
| 66547 | Wamego, KS | 17.3 mi |
| 66407 | Belvue, KS | 17.4 mi |
| 66427 | Frankfort, KS | 17.7 mi |
| 66535 | Saint George, KS | 18.8 mi |
| 66536 | Saint Marys, KS | 19.1 mi |
Questions about 66521
What is the ZIP+4 code for 66521?
66521 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 66521, you need to look up a specific street address to get them.
What city is 66521?
66521 is assigned to Onaga, Kansas, in Pottawatomie 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.