ZIP Code 21711 — Big Pool, MD
21711 is a standard (street delivery) ZIP code serving Big Pool, Maryland, in Washington 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 21711 at a glance
| ZIP code | 21711 |
|---|---|
| Primary city | Big Pool |
| State | Maryland (MD) |
| County | Washington FIPS 24043 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 929 |
| Coordinates | 39.668080, -78.012470 |
How ZIP+4 works in 21711
The four digits after the hyphen encode a delivery segment inside 21711. 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 21711 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 21711.
| ZIP | City | Distance |
|---|---|---|
| 21722 | Clear Spring, MD | 5.2 mi |
| 25419 | Falling Waters, WV | 9 mi |
| 17236 | Mercersburg, PA | 9.8 mi |
| 17212 | Big Cove Tannery, PA | 10.3 mi |
| 25427 | Hedgesville, WV | 10.6 mi |
| 21750 | Hancock, MD | 10.7 mi |
| 21795 | Williamsport, MD | 11.5 mi |
| 25403 | Martinsburg, WV | 12.7 mi |
| 25411 | Berkeley Springs, WV | 13.5 mi |
| 25404 | Martinsburg, WV | 13.9 mi |
| 21767 | Maugansville, MD | 14.3 mi |
| 21740 | Hagerstown, MD | 14.7 mi |
Questions about 21711
What is the ZIP+4 code for 21711?
21711 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 21711, you need to look up a specific street address to get them.
What city is 21711?
21711 is assigned to Big Pool, Maryland, in Washington 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.