Gilliam County ZIP Codes

Gilliam County is a county of Oregon.

ZIP codes: 3
Cities & towns: 3
Area codes: 2
Land area: 1,205 sq mi

Every ZIP code in Gilliam County

978xx

The complete list of Gilliam County, OR ZIP codes with the city each one delivers to.
ZIP code	City
97812	Arlington
97823	Condon
97861	Mikkalo

We do not publish a delivery type (standard, PO box, unique) or a neighbourhood for each ZIP. USPS delivery-type products are licensed, and no clean-rights source maps ZIP codes to neighbourhoods — so the Gilliam County codes above are listed without a column we would have to invent.

Cities and towns in Gilliam County

A further 1 place in Gilliam County appears in the postal source without a page of its own; its codes are in the table above and each one links to its own page.

Area codes covering Gilliam County

Telephone and postal boundaries are drawn by different bodies, so these codes overlap the county without matching its edges.

Where Gilliam County's ZIP codes sit

Each point is the reference point of one Gilliam County ZIP code, plotted from its record coordinates. The outline is the convex envelope of those points — a footprint, not a boundary.

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

Scope every ZIP code recorded in Gilliam County. Source GeoNames US postal codes (2026-07 postal dump), Census 2024 county Gazetteer (2024 Gazetteer) and geoinfo-dataset (full_dataset) ZIP→NPA (2018 snapshot). Updated 16 July 2026. The outline is a convex envelope of ZIP reference points, not a jurisdiction boundary.