ZIP Code 61231 — Aledo, IL
61231 is a standard (street delivery) ZIP code serving Aledo, Illinois, in Mercer 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 61231 at a glance
| ZIP code | 61231 |
|---|---|
| Primary city | Aledo |
| State | Illinois (IL) |
| County | Mercer FIPS 17131 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Chicago |
| Population | 4,962 |
| Coordinates | 41.212800, -90.722940 |
How ZIP+4 works in 61231
The four digits after the hyphen encode a delivery segment inside 61231. 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 61231 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 61231.
| ZIP | City | Distance |
|---|---|---|
| 61263 | Matherville, IL | 7.4 mi |
| 61486 | Viola, IL | 7.7 mi |
| 61279 | Reynolds, IL | 7.8 mi |
| 61260 | Joy, IL | 8.6 mi |
| 61476 | Seaton, IL | 10.1 mi |
| 61276 | Preemption, IL | 10.5 mi |
| 61237 | Buffalo Prairie, IL | 11.5 mi |
| 61412 | Alexis, IL | 12 mi |
| 61281 | Sherrard, IL | 12.2 mi |
| 61284 | Taylor Ridge, IL | 12.5 mi |
| 61442 | Keithsburg, IL | 12.9 mi |
| 61465 | New Windsor, IL | 13.3 mi |
Questions about 61231
What is the ZIP+4 code for 61231?
61231 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 61231, you need to look up a specific street address to get them.
What city is 61231?
61231 is assigned to Aledo, Illinois, in Mercer 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.