ZIP Code 21056 — Gibson Island, MD
21056 is a standard (street delivery) ZIP code serving Gibson Island, Maryland, in Anne Arundel 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 21056 at a glance
| ZIP code | 21056 |
|---|---|
| Primary city | Gibson Island |
| State | Maryland (MD) |
| County | Anne Arundel FIPS 24003 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 291 |
| Coordinates | 39.078050, -76.433800 |
How ZIP+4 works in 21056
The four digits after the hyphen encode a delivery segment inside 21056. 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 21056 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 21056.
| ZIP | City | Distance |
|---|---|---|
| 21409 | Annapolis, MD | 4.1 mi |
| 21012 | Arnold, MD | 4.1 mi |
| 21122 | Pasadena, MD | 4.4 mi |
| 21402 | Annapolis, MD | 6.5 mi |
| 21146 | Severna Park, MD | 6.6 mi |
| 21405 | Annapolis, MD | 7 mi |
| 21052 | Fort Howard, MD | 8.6 mi |
| 21401 | Annapolis, MD | 8.7 mi |
| 21032 | Crownsville, MD | 9.6 mi |
| 21403 | Annapolis, MD | 9.8 mi |
| 21108 | Millersville, MD | 10.1 mi |
| 21060 | Glen Burnie, MD | 10.2 mi |
Questions about 21056
What is the ZIP+4 code for 21056?
21056 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 21056, you need to look up a specific street address to get them.
What city is 21056?
21056 is assigned to Gibson Island, Maryland, in Anne Arundel 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.