ZIP Code 18421 — Forest City, PA
18421 is a standard (street delivery) ZIP code serving Forest City, Pennsylvania, in Susquehanna 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 18421 at a glance
| ZIP code | 18421 |
|---|---|
| Primary city | Forest City |
| State | Pennsylvania (PA) |
| County | Susquehanna FIPS 42115 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 4,603 |
| Coordinates | 41.663370, -75.469100 |
How ZIP+4 works in 18421
The four digits after the hyphen encode a delivery segment inside 18421. 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 18421 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 18421.
| ZIP | City | Distance |
|---|---|---|
| 18413 | Clifford, PA | 3.4 mi |
| 18407 | Carbondale, PA | 5.4 mi |
| 18430 | Herrick Center, PA | 5.5 mi |
| 18470 | Union Dale, PA | 5.8 mi |
| 18472 | Waymart, PA | 6.3 mi |
| 18456 | Prompton, PA | 7.3 mi |
| 18441 | Lenoxville, PA | 8.1 mi |
| 18453 | Pleasant Mount, PA | 8.2 mi |
| 18433 | Jermyn, PA | 8.7 mi |
| 18842 | South Gibson, PA | 9.9 mi |
| 18454 | Poyntelle, PA | 11 mi |
| 18431 | Honesdale, PA | 11.4 mi |
Questions about 18421
What is the ZIP+4 code for 18421?
18421 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 18421, you need to look up a specific street address to get them.
What city is 18421?
18421 is assigned to Forest City, Pennsylvania, in Susquehanna 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.