ZIP Code 21155 — Upperco, MD
21155 is a standard (street delivery) ZIP code serving Upperco, Maryland, in Baltimore 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 21155 at a glance
| ZIP code | 21155 |
|---|---|
| Primary city | Upperco |
| State | Maryland (MD) |
| County | Baltimore FIPS 24005 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 3,313 |
| Coordinates | 39.571830, -76.805970 |
How ZIP+4 works in 21155
The four digits after the hyphen encode a delivery segment inside 21155. 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 21155 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 21155.
| ZIP | City | Distance |
|---|---|---|
| 21074 | Hampstead, MD | 3.7 mi |
| 21023 | Butler, MD | 4.8 mi |
| 21136 | Reisterstown, MD | 5.8 mi |
| 21071 | Glyndon, MD | 6 mi |
| 21152 | Sparks Glencoe, MD | 6.8 mi |
| 21048 | Finksburg, MD | 7.7 mi |
| 21102 | Manchester, MD | 8.2 mi |
| 21120 | Parkton, MD | 8.6 mi |
| 21030 | Cockeysville, MD | 9.3 mi |
| 21157 | Westminster, MD | 9.5 mi |
| 21053 | Freeland, MD | 9.6 mi |
| 21031 | Hunt Valley, MD | 9.8 mi |
Questions about 21155
What is the ZIP+4 code for 21155?
21155 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 21155, you need to look up a specific street address to get them.
What city is 21155?
21155 is assigned to Upperco, Maryland, in Baltimore 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.