ZIP Code 20678 — Prince Frederick, MD
20678 is a standard (street delivery) ZIP code serving Prince Frederick, Maryland, in Calvert 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 20678 at a glance
| ZIP code | 20678 |
|---|---|
| Primary city | Prince Frederick |
| State | Maryland (MD) |
| County | Calvert FIPS 24009 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 12,752 |
| Coordinates | 38.521640, -76.600720 |
How ZIP+4 works in 20678
The four digits after the hyphen encode a delivery segment inside 20678. 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 20678 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 20678.
| ZIP | City | Distance |
|---|---|---|
| 20676 | Port Republic, MD | 3.7 mi |
| 20612 | Benedict, MD | 4.3 mi |
| 20639 | Huntingtown, MD | 6 mi |
| 20685 | Saint Leonard, MD | 7.1 mi |
| 20608 | Aquasco, MD | 7.3 mi |
| 20615 | Broomes Island, MD | 7.5 mi |
| 20637 | Hughesville, MD | 9.6 mi |
| 20732 | Chesapeake Beach, MD | 9.8 mi |
| 20659 | Mechanicsville, MD | 10 mi |
| 20689 | Sunderland, MD | 10.2 mi |
| 20636 | Hollywood, MD | 11.5 mi |
| 20736 | Owings, MD | 11.8 mi |
Questions about 20678
What is the ZIP+4 code for 20678?
20678 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 20678, you need to look up a specific street address to get them.
What city is 20678?
20678 is assigned to Prince Frederick, Maryland, in Calvert 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.