ZIP Code 21723

21723 is one of Maryland's ZIP codes, delivering to addresses in Cooksville, Howard County.

City: Cooksville
County: Howard County
State: Maryland
Prefix: 217xx

Where this code sits

21723 is part of the 217xx range, the group of codes handled by one mail processing centre. It is the only ZIP code delivering to Cooksville.

Area codes over the same ground

Postal and telephone geography are drawn separately, so these codes cover the area 21723 delivers to without sharing its boundary.

ZIP codes nearest 21723

The ZIP codes whose reference points sit closest to 21723.
ZIP code	Distance	Delivers to
ZIP code 21794	2.8 mi	West Friendship, MD
ZIP code 21738	2.9 mi	Glenwood, MD
ZIP code 21797	3.6 mi	Woodbine, MD
ZIP code 21765	3.8 mi	Lisbon, MD
ZIP code 21737	4.7 mi	Glenelg, MD
ZIP code 21104	5.0 mi	Marriottsville, MD
ZIP code 21036	6.0 mi	Dayton, MD
ZIP code 21041	6.8 mi	Ellicott City, 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 21723, plotted from its record coordinates.

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

Scope ZIP code 21723. 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.