ZIP Code 21758 — Knoxville, MD
21758 is a standard (street delivery) ZIP code serving Knoxville, Maryland, in Washington 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 21758 at a glance
| ZIP code | 21758 |
|---|---|
| Primary city | Knoxville |
| State | Maryland (MD) |
| County | Washington FIPS 24043 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 4,409 |
| Coordinates | 39.345670, -77.662650 |
How ZIP+4 works in 21758
The four digits after the hyphen encode a delivery segment inside 21758. 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 21758 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 21758.
| ZIP | City | Distance |
|---|---|---|
| 21715 | Brownsville, MD | 2.3 mi |
| 21716 | Brunswick, MD | 2.7 mi |
| 21718 | Burkittsville, MD | 3.8 mi |
| 21755 | Jefferson, MD | 5.1 mi |
| 20180 | Lovettsville, VA | 5.5 mi |
| 21779 | Rohrersville, MD | 5.5 mi |
| 25432 | Millville, WV | 7.5 mi |
| 21756 | Keedysville, MD | 8 mi |
| 25425 | Harpers Ferry, WV | 8.4 mi |
| 21777 | Point Of Rocks, MD | 8.5 mi |
| 21769 | Middletown, MD | 8.7 mi |
| 25442 | Shenandoah Junction, WV | 9.2 mi |
Questions about 21758
What is the ZIP+4 code for 21758?
21758 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 21758, you need to look up a specific street address to get them.
What city is 21758?
21758 is assigned to Knoxville, Maryland, in Washington 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.