99128 ZIP Code: Farmington, Washington
ZIP code 99128 covers Farmington, Washington. It sits in Whitman County. A ZIP code is a US Postal Service mail route, not a boundary on a map, so it describes where post is delivered rather than an administrative area.
| ZIP code | 99128 |
|---|---|
| Place | Farmington |
| State | Washington (WA) |
| County or equivalent | Whitman County |
| Phone area codes in Washington | 6 |
| Country | United States |
ZIP codes near 99128
- 99104 Belmontabout 5 miles
- 99130 Garfieldabout 7 miles
- 99158 Oakesdaleabout 8 miles
- 83824 Desmet, IDabout 9 miles
- 99033 Tekoaabout 10 miles
- 83870 Tensed, IDabout 10 miles
- 99161 Palouseabout 12 miles
- 83855 Potlatch, IDabout 12 miles
Distances are straight-line, between the approximate centres of each delivery area.
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Frequently asked questions
Where is ZIP code 99128?
ZIP code 99128 is in Farmington, Washington, in Whitman County. ZIP codes are mail delivery routes rather than mapped regions, so the code identifies a set of addresses the Postal Service serves together, not a district with fixed borders.
What county is 99128 in?
99128 is in Whitman County, Washington. A single ZIP code can straddle a county line, because mail routes were drawn for delivery efficiency and take no notice of county boundaries, so the county shown is the one the code is primarily associated with.
What area code goes with ZIP code 99128?
ZIP codes and telephone area codes are separate systems with different boundaries, so no ZIP code maps to exactly one area code. Washington uses 6 geographic area codes: 206, 253, 360, 425, 509 and 564.
Is 99128 a real ZIP code?
Yes. 99128 appears in the GeoNames postal-code dataset as an active US code assigned to Farmington, Washington. Codes that have been retired or never issued do not appear, which is why entering one on this site returns a not-found page rather than a blank record.
Why do ZIP code boundaries look odd on maps?
Because they are not boundaries. A ZIP code is a collection of mail routes, and a route is a line a carrier walks or drives, not an area. Any ZIP code map you have seen is somebody's approximation drawn around the addresses in a code, which is also why two ZIP code maps rarely agree with each other.
Can two addresses in the same ZIP code be in different cities?
Yes, routinely. The Postal Service assigns a preferred city name to each code for addressing purposes, and that name often covers several neighbouring towns, unincorporated areas or a whole postal district. The place shown here is the one the source names for the code, not a claim that every address in it is inside that town's limits.
ZIP code, place, county and location data from GeoNames, used under CC BY 4.0, extracted 2026-08-22. ZIP codes are Postal Service delivery routes, not administrative areas, so a code can cross city and county lines and the place name shown is the one the source records for the code. Coordinates are an approximate centre of the delivery area, not a precise location. Population and time zone are not shown because the source does not publish them.