Sioux City Iowa ZIP Codes

Sioux City holds 9 ZIP codes, all inside one county and one postal prefix.

We do not publish a delivery type (standard, PO box, unique) or a neighbourhood for each ZIP.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

Scope every ZIP code recorded for Sioux City. Source GeoNames US postal codes (2026-07 postal dump) and Census 2024 county Gazetteer (2024 Gazetteer). Updated 15 July 2026. ZIP codes are delivery-route groupings, not areas; the boundaries implied by any ZIP map are approximations.

Every Sioux City ZIP code begins 511. Those first three digits identify the sectional center facility that processes mail for this part of Iowa. No other Iowa community draws on the 511xx range — it belongs entirely to Sioux City.

Every Iowa ZIP prefix and the region it covers →

ZIP codes and area codes are separate systems — one routes mail, the other routes calls — and they do not share boundaries. The code below serves the same ground Sioux City occupies.

• 712 Area code 712

Sioux City Iowa area codes in full →

Straight-line distance between place reference points, not driving distance.