ZIP Code 51101

51101 is one of Iowa's ZIP codes, delivering to addresses in Sioux City, Woodbury County.

City: Sioux City
County: Woodbury County
State: Iowa
Prefix: 511xx

Where this code sits

51101 is part of the 511xx range, the group of codes handled by one mail processing centre. Sioux City is served by 9 ZIP codes in total; the full list, with the county each falls in, is on the Sioux City page.

Sioux City Iowa ZIP codes →

Area codes over the same ground

Postal and telephone geography are drawn separately, so these codes cover the area 51101 delivers to without sharing its boundary.

712 Area code 712

ZIP codes nearest 51101

The ZIP codes whose reference points sit closest to 51101.
ZIP code	Distance	Delivers to
ZIP code 51105	1.1 mi	Sioux City, IA
ZIP code 51103	1.5 mi	Sioux City, IA
ZIP code 51104	2.0 mi	Sioux City, IA
ZIP code 68776	2.3 mi	South Sioux City, NE
ZIP code 51106	3.3 mi	Sioux City, IA
ZIP code 51108	4.0 mi	Sioux City, IA
ZIP code 51109	4.2 mi	Sioux City, IA
ZIP code 57049	5.7 mi	North Sioux City, SD

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 51101, plotted from its record coordinates.

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

Scope ZIP code 51101. 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.