ZIP Code 21704 — Frederick, MD
21704 is a standard (street delivery) ZIP code serving Frederick, Maryland, in Frederick 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 21704 at a glance
| ZIP code | 21704 |
|---|---|
| Primary city | Frederick |
| State | Maryland (MD) |
| County | Frederick FIPS 24021 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 20,006 |
| Coordinates | 39.350600, -77.373500 |
How ZIP+4 works in 21704
The four digits after the hyphen encode a delivery segment inside 21704. 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 21704 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.
Other ZIP codes in Frederick
Nearby ZIP codes
Showing the closest twelve. See every ZIP code within 25 miles of 21704.
| ZIP | City | Distance |
|---|---|---|
| 21717 | Buckeystown, MD | 3.2 mi |
| 21754 | Ijamsville, MD | 3.5 mi |
| 21705 | Frederick, MD | 4.5 mi |
| 21703 | Frederick, MD | 5.4 mi |
| 21710 | Adamstown, MD | 5.5 mi |
| 21770 | Monrovia, MD | 6.2 mi |
| 21774 | New Market, MD | 6.5 mi |
| 21701 | Frederick, MD | 7 mi |
| 20871 | Clarksburg, MD | 8 mi |
| 21714 | Braddock Heights, MD | 8.4 mi |
| 20838 | Barnesville, MD | 8.8 mi |
| 21790 | Tuscarora, MD | 9.1 mi |
Questions about 21704
What is the ZIP+4 code for 21704?
21704 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 21704, you need to look up a specific street address to get them.
What city is 21704?
21704 is assigned to Frederick, Maryland, in Frederick 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.