ZIP Code 21821 — Deal Island, MD
21821 is a standard (street delivery) ZIP code serving Deal Island, Maryland, in Somerset 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 21821 at a glance
| ZIP code | 21821 |
|---|---|
| Primary city | Deal Island |
| State | Maryland (MD) |
| County | Somerset FIPS 24039 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 797 |
| Coordinates | 38.166640, -75.906110 |
How ZIP+4 works in 21821
The four digits after the hyphen encode a delivery segment inside 21821. 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 21821 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 21821.
| ZIP | City | Distance |
|---|---|---|
| 21840 | Nanticoke, MD | 6.4 mi |
| 21867 | Upper Fairmount, MD | 7.2 mi |
| 21814 | Bivalve, MD | 8.7 mi |
| 21865 | Tyaskin, MD | 9.1 mi |
| 21627 | Crocheron, MD | 9.1 mi |
| 21871 | Westover, MD | 10.4 mi |
| 21853 | Princess Anne, MD | 10.9 mi |
| 21890 | Westover, MD | 11.2 mi |
| 21672 | Toddville, MD | 11.4 mi |
| 21675 | Wingate, MD | 13.1 mi |
| 21856 | Quantico, MD | 13.3 mi |
| 21817 | Crisfield, MD | 13.4 mi |
Questions about 21821
What is the ZIP+4 code for 21821?
21821 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 21821, you need to look up a specific street address to get them.
What city is 21821?
21821 is assigned to Deal Island, Maryland, in Somerset 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.