ZIP Code 99128 — Farmington, WA
99128 is a standard (street delivery) ZIP code serving Farmington, Washington, in Whitman 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 99128 at a glance
| ZIP code | 99128 |
|---|---|
| Primary city | Farmington |
| State | Washington (WA) |
| County | Whitman FIPS 53075 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Los_Angeles |
| Population | 259 |
| Coordinates | 47.100450, -117.085230 |
How ZIP+4 works in 99128
The four digits after the hyphen encode a delivery segment inside 99128. 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 99128 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 99128.
| ZIP | City | Distance |
|---|---|---|
| 83824 | Desmet, ID | 6.9 mi |
| 99158 | Oakesdale, WA | 7.6 mi |
| 99130 | Garfield, WA | 8.4 mi |
| 99033 | Tekoa, WA | 9 mi |
| 83870 | Tensed, ID | 11.2 mi |
| 83855 | Potlatch, ID | 11.6 mi |
| 99018 | Latah, WA | 13.6 mi |
| 99174 | Steptoe, WA | 14.3 mi |
| 99161 | Palouse, WA | 14.3 mi |
| 99176 | Thornton, WA | 15.4 mi |
| 83851 | Plummer, ID | 16.1 mi |
| 83872 | Viola, ID | 17.6 mi |
Questions about 99128
What is the ZIP+4 code for 99128?
99128 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 99128, you need to look up a specific street address to get them.
What city is 99128?
99128 is assigned to Farmington, Washington, in Whitman 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.