ZIP Code 21648 — Madison, MD
21648 is a standard (street delivery) ZIP code serving Madison, Maryland, in Dorchester 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 21648 at a glance
| ZIP code | 21648 |
|---|---|
| Primary city | Madison |
| State | Maryland (MD) |
| County | Dorchester FIPS 24019 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 172 |
| Coordinates | 38.496600, -76.233860 |
How ZIP+4 works in 21648
The four digits after the hyphen encode a delivery segment inside 21648. 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 21648 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 21648.
| ZIP | City | Distance |
|---|---|---|
| 21677 | Woolford, MD | 2.7 mi |
| 21669 | Taylors Island, MD | 3.8 mi |
| 21622 | Church Creek, MD | 6.9 mi |
| 21613 | Cambridge, MD | 8.8 mi |
| 21626 | Crapo, MD | 13.6 mi |
| 20657 | Lusby, MD | 13.8 mi |
| 21654 | Oxford, MD | 14.6 mi |
| 21671 | Tilghman, MD | 14.9 mi |
| 21673 | Trappe, MD | 14.9 mi |
| 21662 | Royal Oak, MD | 15.1 mi |
| 21634 | Fishing Creek, MD | 15.2 mi |
| 21652 | Neavitt, MD | 15.6 mi |
Questions about 21648
What is the ZIP+4 code for 21648?
21648 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 21648, you need to look up a specific street address to get them.
What city is 21648?
21648 is assigned to Madison, Maryland, in Dorchester 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.