ZIP Code 21664

21664 is one of Maryland's ZIP codes, delivering to addresses in Secretary, Dorchester County.

City: Secretary
County: Dorchester County
State: Maryland
Prefix: 216xx

Where this code sits

21664 is part of the 216xx range, the group of codes handled by one mail processing centre. It is the only ZIP code delivering to Secretary.

Secretary Maryland ZIP codes →

Area codes over the same ground

Postal and telephone geography are drawn separately, so these codes cover the area 21664 delivers to without sharing its boundary.

ZIP codes nearest 21664

The ZIP codes whose reference points sit closest to 21664.
ZIP code	Distance	Delivers to
ZIP code 21631	1.3 mi	East New Market, MD
ZIP code 21835	4.8 mi	Linkwood, MD
ZIP code 21643	5.1 mi	Hurlock, MD
ZIP code 21673	6.8 mi	Trappe, MD
ZIP code 21613	8.2 mi	Cambridge, MD
ZIP code 21609	9.1 mi	Bethlehem, MD
ZIP code 21659	9.3 mi	Rhodesdale, MD
ZIP code 21655	9.6 mi	Preston, MD

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 21664, plotted from its record coordinates.

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

Scope ZIP code 21664. 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.