ZIP Code 45820 — Cairo, OH
45820 is a standard (street delivery) ZIP code serving Cairo, Ohio, in Allen 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 45820 at a glance
| ZIP code | 45820 |
|---|---|
| Primary city | Cairo |
| State | Ohio (OH) |
| County | Allen FIPS 39003 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 581 |
| Coordinates | 40.830740, -84.084730 |
How ZIP+4 works in 45820
The four digits after the hyphen encode a delivery segment inside 45820. 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 45820 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 45820.
| ZIP | City | Distance |
|---|---|---|
| 45801 | Lima, OH | 4.6 mi |
| 45807 | Lima, OH | 4.6 mi |
| 45893 | Vaughnsville, OH | 4.7 mi |
| 45830 | Columbus Grove, OH | 5.2 mi |
| 45809 | Gomer, OH | 5.3 mi |
| 45808 | Beaverdam, OH | 5.8 mi |
| 45804 | Lima, OH | 8 mi |
| 45805 | Lima, OH | 8.1 mi |
| 45854 | Lafayette, OH | 8.5 mi |
| 45806 | Lima, OH | 10.9 mi |
| 45817 | Bluffton, OH | 11 mi |
| 45877 | Pandora, OH | 11.5 mi |
Questions about 45820
What is the ZIP+4 code for 45820?
45820 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 45820, you need to look up a specific street address to get them.
What city is 45820?
45820 is assigned to Cairo, Ohio, in Allen 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.