ZIP Code 52309 — Monmouth, IA
52309 is a standard (street delivery) ZIP code serving Monmouth, Iowa, in Jackson 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 52309 at a glance
| ZIP code | 52309 |
|---|---|
| Primary city | Monmouth |
| State | Iowa (IA) |
| County | Jackson FIPS 19097 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Chicago |
| Population | 443 |
| Coordinates | 42.124150, -90.887330 |
How ZIP+4 works in 52309
The four digits after the hyphen encode a delivery segment inside 52309. 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 52309 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 52309.
| ZIP | City | Distance |
|---|---|---|
| 52207 | Baldwin, IA | 3.6 mi |
| 52321 | Onslow, IA | 5 mi |
| 52362 | Wyoming, IA | 7.4 mi |
| 52323 | Oxford Junction, IA | 10.2 mi |
| 52212 | Center Junction, IA | 10.4 mi |
| 52060 | Maquoketa, IA | 10.7 mi |
| 52032 | Bernard, IA | 11.7 mi |
| 52033 | Cascade, IA | 12.2 mi |
| 52254 | Lost Nation, IA | 12.6 mi |
| 52079 | Zwingle, IA | 14.2 mi |
| 52030 | Andrew, IA | 15.2 mi |
| 52320 | Olin, IA | 15.8 mi |
Questions about 52309
What is the ZIP+4 code for 52309?
52309 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 52309, you need to look up a specific street address to get them.
What city is 52309?
52309 is assigned to Monmouth, Iowa, in Jackson 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.