ZIP Code 57421

57421 is one of South Dakota's ZIP codes, delivering to addresses in Amherst, Marshall County.

City: Amherst
County: Marshall County
State: South Dakota
Prefix: 574xx

Where this code sits

57421 is part of the 574xx range, the group of codes handled by one mail processing centre. It is the only ZIP code delivering to Amherst.

Area codes over the same ground

Postal and telephone geography are drawn separately, so these codes cover the area 57421 delivers to without sharing its boundary.

605 Area code 605

ZIP codes nearest 57421

The ZIP codes whose reference points sit closest to 57421.
ZIP code	Distance	Delivers to
ZIP code 57432	8.4 mi	Claremont, SD
ZIP code 57449	8.5 mi	Houghton, SD
ZIP code 57430	9.4 mi	Britton, SD
ZIP code 57454	12 mi	Langford, SD
ZIP code 57446	15 mi	Hecla, SD
ZIP code 57468	19 mi	Pierpont, SD
ZIP code 57433	20 mi	Columbia, SD
ZIP code 58043	21 mi	Havana, ND

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 57421, plotted from its record coordinates.

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

Scope ZIP code 57421. 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.