Washington County ZIP Codes

Washington County is a county of Missouri.

ZIP codes: 8
Cities & towns: 8
Area codes: 3
Land area: 760 sq mi

Every ZIP code in Washington County

630xx–636xx

The complete list of Washington County, MO ZIP codes with the city each one delivers to.
ZIP code	City
63071	Richwoods
63622	Belgrade
63630	Cadet
63631	Caledonia
63648	Irondale
63660	Mineral Point
63664	Potosi
63674	Tiff

We do not publish a delivery type (standard, PO box, unique) or a neighbourhood for each ZIP.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 Washington County codes above are listed without a column we would have to invent.

Cities and towns in Washington County

A further 4 places in Washington County appear in the postal source without a page of its own; their codes are in the table above and each one links to its own page.

Area codes covering Washington County

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

Where Washington County's ZIP codes sit

Each point is the reference point of one Washington 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 Washington 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.