ZIP Code 99643 — Old Harbor, AK
99643 is a standard (street delivery) ZIP code serving Old Harbor, Alaska, in Kodiak Island 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 99643 at a glance
| ZIP code | 99643 |
|---|---|
| Primary city | Old Harbor |
| State | Alaska (AK) |
| County | Kodiak Island FIPS 02150 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Anchorage |
| Population | 162 |
| Coordinates | 57.216690, -153.326580 |
How ZIP+4 works in 99643
The four digits after the hyphen encode a delivery segment inside 99643. 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 99643 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 99643.
| ZIP | City | Distance |
|---|---|---|
| 99615 | Kodiak, AK | 25 mi |
| 99624 | Larsen Bay, AK | 25.5 mi |
Questions about 99643
What is the ZIP+4 code for 99643?
99643 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 99643, you need to look up a specific street address to get them.
What city is 99643?
99643 is assigned to Old Harbor, Alaska, in Kodiak Island 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.