ZIP Code 99328

99328 is one of Washington's ZIP codes, delivering to addresses in Dayton, Columbia County.

City: Dayton
County: Columbia County
State: Washington
Prefix: 993xx

Where this code sits

99328 is part of the 993xx range, the group of codes handled by one mail processing centre. It is the only ZIP code delivering to Dayton.

Dayton Washington ZIP codes →

Area codes over the same ground

Postal and telephone geography are drawn separately, so these codes cover the area 99328 delivers to without sharing its boundary.

509 Area code 509

ZIP codes nearest 99328

The ZIP codes whose reference points sit closest to 99328.
ZIP code	Distance	Delivers to
ZIP code 99361	8.6 mi	Waitsburg, WA
ZIP code 99329	14 mi	Dixie, WA
ZIP code 99359	16 mi	Starbuck, WA
ZIP code 99348	21 mi	Prescott, WA
ZIP code 99347	21 mi	Pomeroy, WA
ZIP code 99362	24 mi	Walla Walla, WA
ZIP code 99136	27 mi	Hay, WA
ZIP code 99324	28 mi	College Place, WA

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 99328, plotted from its record coordinates.

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

Scope ZIP code 99328. 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.