Mason City Iowa ZIP Codes
Mason City holds 2 ZIP codes, all inside one county and one postal prefix.
Every ZIP code in Mason City
| ZIP code | County |
|---|---|
| 50401 | Cerro Gordo County |
| 50402 | Cerro Gordo County |
We do not publish a delivery type (standard, PO box, unique) or a neighbourhood for each ZIP.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 Mason City codes above are listed without a column we would have to invent.
Scope every ZIP code recorded for Mason City. Source GeoNames US postal codes (2026-07 postal dump) and Census 2024 county Gazetteer (2024 Gazetteer). Updated . ZIP codes are delivery-route groupings, not areas; the boundaries implied by any ZIP map are approximations.
How these codes cluster
Every Mason City ZIP code begins 504. Those first three digits identify the sectional center facility that processes mail for this part of Iowa. Statewide that range covers 57 ZIP codes, so Mason City accounts for 4% of it.
Every Iowa ZIP prefix and the region it covers →
Area codes covering Mason City
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 Mason City occupies.
Mason City Iowa area codes in full →
Where Mason City's ZIP codes sit
- Reference points and footprint
- Not an official NANPA boundary
- Not a USPS delivery area
Cities near Mason City
| City | Distance | ZIP codes |
|---|---|---|
| Rock Falls Iowa ZIP codes | 7.0 mi | 1 ZIP code |
| Plymouth Iowa ZIP codes | 7.8 mi | 1 ZIP code |
| Clear Lake Iowa ZIP codes | 8.8 mi | 1 ZIP code |
| Nora Springs Iowa ZIP codes | 9.7 mi | 1 ZIP code |
| Manly Iowa ZIP codes | 9.7 mi | 1 ZIP code |
| Hanlontown Iowa ZIP codes | 13 mi | 1 ZIP code |
| Swaledale Iowa ZIP codes | 13 mi | 1 ZIP code |
| Ventura Iowa ZIP codes | 14 mi | 1 ZIP code |
Straight-line distance between place reference points, not driving distance.