ZIP Code 06378 — Stonington, CT
06378 is a standard (street delivery) ZIP code serving Stonington, Connecticut, in Southeastern Connecticut 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 06378 at a glance
| ZIP code | 06378 |
|---|---|
| Primary city | Stonington |
| State | Connecticut (CT) |
| County | Southeastern Connecticut FIPS 09180 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 5,555 |
| Coordinates | 41.380390, -71.913760 |
How ZIP+4 works in 06378
The four digits after the hyphen encode a delivery segment inside 06378. 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 06378 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 06378.
| ZIP | City | Distance |
|---|---|---|
| 06379 | Pawcatuck, CT | 3 mi |
| 06355 | Mystic, CT | 3.2 mi |
| 06339 | Ledyard, CT | 6.2 mi |
| 02891 | Westerly, RI | 6.3 mi |
| 06359 | North Stonington, CT | 6.5 mi |
| 06338 | Mashantucket, CT | 6.6 mi |
| 06340 | Groton, CT | 7 mi |
| 02804 | Ashaway, RI | 8.3 mi |
| 06335 | Gales Ferry, CT | 8.4 mi |
| 06390 | Fishers Island, NY | 8.5 mi |
| 02808 | Bradford, RI | 8.8 mi |
| 02833 | Hopkinton, RI | 9.9 mi |
Questions about 06378
What is the ZIP+4 code for 06378?
06378 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 06378, you need to look up a specific street address to get them.
What city is 06378?
06378 is assigned to Stonington, Connecticut, in Southeastern Connecticut 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.