ZIP Code 51040

51040 is one of Iowa's ZIP codes, delivering to addresses in Onawa, Monona County.

City: Onawa
County: Monona County
State: Iowa
Prefix: 510xx

Where this code sits

51040 is part of the 510xx range, the group of codes handled by one mail processing centre. It is the only ZIP code delivering to Onawa.

Onawa Iowa ZIP codes →

Area codes over the same ground

Postal and telephone geography are drawn separately, so these codes cover the area 51040 delivers to without sharing its boundary.

712 Area code 712

ZIP codes nearest 51040

The ZIP codes whose reference points sit closest to 51040.
ZIP code	Distance	Delivers to
ZIP code 51523	7.9 mi	Blencoe, IA
ZIP code 68020	8.3 mi	Decatur, NE
ZIP code 51063	8.8 mi	Whiting, IA
ZIP code 51010	11 mi	Castana, IA
ZIP code 51051	13 mi	Rodney, IA
ZIP code 68039	14 mi	Macy, NE
ZIP code 51055	16 mi	Sloan, IA
ZIP code 51056	16 mi	Smithland, IA

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 51040, plotted from its record coordinates.

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

Scope ZIP code 51040. 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.