ZIP Code 03878 — Somersworth, NH
03878 is a standard (street delivery) ZIP code serving Somersworth, New Hampshire, in Strafford 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 03878 at a glance
| ZIP code | 03878 |
|---|---|
| Primary city | Somersworth |
| State | New Hampshire (NH) |
| County | Strafford FIPS 33017 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 12,205 |
| Coordinates | 43.253350, -70.885550 |
How ZIP+4 works in 03878
The four digits after the hyphen encode a delivery segment inside 03878. 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 03878 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 03878.
| ZIP | City | Distance |
|---|---|---|
| 03869 | Rollinsford, NH | 3.2 mi |
| 03901 | Berwick, ME | 3.9 mi |
| 03820 | Dover, NH | 4.4 mi |
| 03839 | Rochester, NH | 4.9 mi |
| 03868 | Rochester, NH | 5.3 mi |
| 03823 | Madbury, NH | 6.1 mi |
| 03867 | Rochester, NH | 6.2 mi |
| 03908 | South Berwick, ME | 7 mi |
| 03906 | North Berwick, ME | 8.3 mi |
| 03825 | Barrington, NH | 8.3 mi |
| 03903 | Eliot, ME | 8.8 mi |
| 03824 | Durham, NH | 9.5 mi |
Questions about 03878
What is the ZIP+4 code for 03878?
03878 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 03878, you need to look up a specific street address to get them.
What city is 03878?
03878 is assigned to Somersworth, New Hampshire, in Strafford 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.