ZIP Code 04421 — Castine, ME
04421 is a standard (street delivery) ZIP code serving Castine, Maine, in Hancock 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 04421 at a glance
| ZIP code | 04421 |
|---|---|
| Primary city | Castine |
| State | Maine (ME) |
| County | Hancock FIPS 23009 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 1,362 |
| Coordinates | 44.411100, -68.795240 |
How ZIP+4 works in 04421
The four digits after the hyphen encode a delivery segment inside 04421. 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 04421 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 04421.
| ZIP | City | Distance |
|---|---|---|
| 04617 | Brooksville, ME | 4.3 mi |
| 04642 | Harborside, ME | 5 mi |
| 04476 | Penobscot, ME | 6.2 mi |
| 04974 | Searsport, ME | 8.6 mi |
| 04676 | Sedgwick, ME | 8.7 mi |
| 04848 | Islesboro, ME | 8.9 mi |
| 04981 | Stockton Springs, ME | 8.9 mi |
| 04650 | Little Deer Isle, ME | 9.3 mi |
| 04673 | Sargentville, ME | 9.6 mi |
| 04614 | Blue Hill, ME | 10.5 mi |
| 04683 | Sunset, ME | 12.2 mi |
| 04431 | East Orland, ME | 12.3 mi |
Questions about 04421
What is the ZIP+4 code for 04421?
04421 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 04421, you need to look up a specific street address to get them.
What city is 04421?
04421 is assigned to Castine, Maine, in Hancock 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.