ZIP Code 21661 — Rock Hall, MD
21661 is a standard (street delivery) ZIP code serving Rock Hall, Maryland, in Kent 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 21661 at a glance
| ZIP code | 21661 |
|---|---|
| Primary city | Rock Hall |
| State | Maryland (MD) |
| County | Kent FIPS 24029 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 2,613 |
| Coordinates | 39.129050, -76.219670 |
How ZIP+4 works in 21661
The four digits after the hyphen encode a delivery segment inside 21661. 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 21661 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 21661.
| ZIP | City | Distance |
|---|---|---|
| 21620 | Chestertown, MD | 8.9 mi |
| 21617 | Centreville, MD | 11.1 mi |
| 21056 | Gibson Island, MD | 12 mi |
| 21619 | Chester, MD | 12.6 mi |
| 21638 | Grasonville, MD | 12.7 mi |
| 21052 | Fort Howard, MD | 13 mi |
| 21658 | Queenstown, MD | 13.7 mi |
| 21623 | Church Hill, MD | 13.8 mi |
| 21219 | Sparrows Point, MD | 13.9 mi |
| 21678 | Worton, MD | 13.9 mi |
| 21409 | Annapolis, MD | 14.3 mi |
| 21666 | Stevensville, MD | 14.4 mi |
Questions about 21661
What is the ZIP+4 code for 21661?
21661 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 21661, you need to look up a specific street address to get them.
What city is 21661?
21661 is assigned to Rock Hall, Maryland, in Kent 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.