ZIP Code 15666 — Mount Pleasant, PA
15666 is a standard (street delivery) ZIP code serving Mount Pleasant, 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 15666 at a glance
| ZIP code | 15666 |
|---|---|
| Primary city | Mount Pleasant |
| State | Pennsylvania (PA) |
| County | Westmoreland FIPS 42129 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 15,980 |
| Coordinates | 40.158580, -79.513980 |
How ZIP+4 works in 15666
The four digits after the hyphen encode a delivery segment inside 15666. 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 15666 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 15666.
| ZIP | City | Distance |
|---|---|---|
| 15674 | Norvelt, PA | 3.4 mi |
| 15688 | Tarrs, PA | 3.9 mi |
| 15612 | Alverton, PA | 4.7 mi |
| 15689 | United, PA | 4.8 mi |
| 15610 | Acme, PA | 5.4 mi |
| 15639 | Hunker, PA | 5.5 mi |
| 15616 | Armbrust, PA | 5.6 mi |
| 15683 | Scottdale, PA | 5.9 mi |
| 15631 | Everson, PA | 6.1 mi |
| 15676 | Pleasant Unity, PA | 6.5 mi |
| 15697 | Youngwood, PA | 6.6 mi |
| 15490 | White, PA | 7 mi |
Questions about 15666
What is the ZIP+4 code for 15666?
15666 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 15666, you need to look up a specific street address to get them.
What city is 15666?
15666 is assigned to Mount Pleasant, 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.