ZIP Code 21757 — Keymar, MD
21757 is a standard (street delivery) ZIP code serving Keymar, Maryland, in Carroll 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 21757 at a glance
| ZIP code | 21757 |
|---|---|
| Primary city | Keymar |
| State | Maryland (MD) |
| County | Carroll FIPS 24013 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 2,671 |
| Coordinates | 39.599020, -77.259060 |
How ZIP+4 works in 21757
The four digits after the hyphen encode a delivery segment inside 21757. 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 21757 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 21757.
| ZIP | City | Distance |
|---|---|---|
| 21778 | Rocky Ridge, MD | 4.3 mi |
| 21798 | Woodsboro, MD | 4.7 mi |
| 21791 | Union Bridge, MD | 5.5 mi |
| 21787 | Taneytown, MD | 6.8 mi |
| 21727 | Emmitsburg, MD | 7.3 mi |
| 21762 | Libertytown, MD | 8.2 mi |
| 21788 | Thurmont, MD | 8.5 mi |
| 21793 | Walkersville, MD | 8.8 mi |
| 21776 | New Windsor, MD | 9.9 mi |
| 21701 | Frederick, MD | 11.2 mi |
| 21780 | Sabillasville, MD | 12.3 mi |
| 21158 | Westminster, MD | 12.5 mi |
Questions about 21757
What is the ZIP+4 code for 21757?
21757 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 21757, you need to look up a specific street address to get them.
What city is 21757?
21757 is assigned to Keymar, Maryland, in Carroll 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.