ZIP Code 99128

99128 is one of Washington's ZIP codes, delivering to addresses in Farmington, Whitman County.

City: Farmington
County: Whitman County
State: Washington
Prefix: 991xx

Where this code sits

99128 is part of the 991xx range, the group of codes handled by one mail processing centre. It is the only ZIP code delivering to Farmington.

Farmington Washington ZIP codes →

Area codes over the same ground

Postal and telephone geography are drawn separately, so these codes cover the area 99128 delivers to without sharing its boundary.

509 Area code 509

ZIP codes nearest 99128

The ZIP codes whose reference points sit closest to 99128.
ZIP code	Distance	Delivers to
ZIP code 99104	4.8 mi	Belmont, WA
ZIP code 99130	7.2 mi	Garfield, WA
ZIP code 99158	8.4 mi	Oakesdale, WA
ZIP code 83824	9.0 mi	Desmet, ID
ZIP code 99033	9.8 mi	Tekoa, WA
ZIP code 83870	10 mi	Tensed, ID
ZIP code 99161	12 mi	Palouse, WA
ZIP code 83855	12 mi	Potlatch, ID

Straight-line distance between place reference points, not driving distance. Where a place has no Census Gazetteer point, its postal centroid is used instead.

Each point is the reference point for 99128, plotted from its record coordinates.

Reference points and footprint
Not an official NANPA boundary
Not a USPS delivery area

Scope ZIP code 99128. Source GeoNames US postal codes (2026-07 postal dump) and Census 2024 county Gazetteer (2024 Gazetteer). Updated 15 July 2026. A ZIP code is a set of delivery routes, not an area; the point shown is a record coordinate, not a centre.