ZIP Code 21918 — Conowingo, MD
21918 is a standard (street delivery) ZIP code serving Conowingo, Maryland, in Cecil 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 21918 at a glance
| ZIP code | 21918 |
|---|---|
| Primary city | Conowingo |
| State | Maryland (MD) |
| County | Cecil FIPS 24015 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 4,169 |
| Coordinates | 39.683270, -76.166620 |
How ZIP+4 works in 21918
The four digits after the hyphen encode a delivery segment inside 21918. 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 21918 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 21918.
| ZIP | City | Distance |
|---|---|---|
| 21917 | Colora, MD | 3.7 mi |
| 21034 | Darlington, MD | 3.8 mi |
| 17563 | Peach Bottom, PA | 5.7 mi |
| 21904 | Port Deposit, MD | 6.3 mi |
| 21911 | Rising Sun, MD | 6.8 mi |
| 19362 | Nottingham, PA | 7.1 mi |
| 21160 | Whiteford, MD | 7.7 mi |
| 21078 | Havre De Grace, MD | 7.9 mi |
| 21028 | Churchville, MD | 8.9 mi |
| 17518 | Drumore, PA | 9.7 mi |
| 17314 | Delta, PA | 9.9 mi |
| 21903 | Perryville, MD | 10 mi |
Questions about 21918
What is the ZIP+4 code for 21918?
21918 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 21918, you need to look up a specific street address to get them.
What city is 21918?
21918 is assigned to Conowingo, Maryland, in Cecil 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.