ZIP Code 15642 — Irwin, PA
15642 is a standard (street delivery) ZIP code serving Irwin, Pennsylvania, in Westmoreland 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 15642 at a glance
| ZIP code | 15642 |
|---|---|
| Primary city | Irwin |
| State | Pennsylvania (PA) |
| County | Westmoreland FIPS 42129 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 46,325 |
| Coordinates | 40.320450, -79.721190 |
How ZIP+4 works in 15642
The four digits after the hyphen encode a delivery segment inside 15642. 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 15642 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 15642.
| ZIP | City | Distance |
|---|---|---|
| 15647 | Larimer, PA | 1.5 mi |
| 15692 | Westmoreland City, PA | 2.4 mi |
| 15691 | Wendel, PA | 2.5 mi |
| 15678 | Rillton, PA | 2.5 mi |
| 15615 | Ardara, PA | 2.9 mi |
| 15665 | Manor, PA | 3.3 mi |
| 15611 | Adamsburg, PA | 3.7 mi |
| 15047 | Greenock, PA | 3.9 mi |
| 15637 | Herminie, PA | 4.1 mi |
| 15625 | Darragh, PA | 4.1 mi |
| 15131 | Mckeesport, PA | 4.3 mi |
| 15028 | Coulters, PA | 4.3 mi |
Questions about 15642
What is the ZIP+4 code for 15642?
15642 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 15642, you need to look up a specific street address to get them.
What city is 15642?
15642 is assigned to Irwin, Pennsylvania, in Westmoreland 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.