ZIP codes

ZIP codes in Carroll County, Maryland

Carroll County has 15 ZIP codes. 3 lie entirely inside it and 12 are shared with neighboring counties, so part of their land and their people are elsewhere. About 173,416 people live in the parts inside it (ACS 2020–2024).

By the All Map Tools Team

ZIP codes: 15; With 1% or more of their land inside
Entirely inside: 3; 99% or more of their land
Shared with other counties: 12; Most with Baltimore County (5)
Most populated ZIP: 21784; 39,258 people · Eldersburg
Least populated ZIP: 21757; 2,671 people
Largest ZIP by land: 21157; 78 sq mi · Westminster

Map of the ZIP codes in Carroll County

Entirely in the county (99% or more of its land)
Shared, mostly in this county
Shared, mostly in other counties
Neighboring counties

Open in the interactive tool

Each area is a ZIP code with its number where it fits. Hover over one to see its name.

All ZIP codes in Carroll County

15 ZIP codes in Carroll County, MD, by number
ZIP code	Main city	Population	Land in the county	Residents in the county
21048	Eldersburg	10,481	100%	10,481
21074	Hampstead	14,777	72%	≈ 13,713
21102	Manchester	12,162	77%	≈ 10,300
21104	Eldersburg	6,052	32%	≈ 2,113
21136	Reisterstown	32,088	3.8%	≈ 713
21155	—	3,313	11%	≈ 1,036
21157	Westminster	38,984	100%	38,984
21158	Westminster	22,083	100%	22,083
21757	—	2,671	52%	≈ 1,172
21771	Green Valley	33,031	26%	≈ 13,602
21776	New Windsor	6,261	79%	≈ 5,536
21784	Eldersburg	39,258	82%	≈ 36,337
21787	Taneytown	11,645	87%	≈ 11,231
21791	Union Bridge	5,340	39%	≈ 2,829
21797	Lisbon	8,643	32%	≈ 3,286

ZIP codes shared with other counties

These 12 ZIP codes have part of their land in another county. The first figure is the share of their land in Carroll County; then, where the rest lies.

21074 (Hampstead): 72% here; 28% in Baltimore County.
21102 (Manchester): 77% here; 23% in Baltimore County.
21104 (Eldersburg): 32% here; 53% in Howard County and 15% in Baltimore County.
21136 (Reisterstown): 3.8% here; 96% in Baltimore County.
21155: 11% here; 89% in Baltimore County.
21757: 52% here; 48% in Frederick County.
21771 (Green Valley): 26% here; 51% in Frederick County, 18% in Howard County, and 4.2% in Montgomery County.
21776 (New Windsor): 79% here; 21% in Frederick County.
21784 (Eldersburg): 82% here; 18% in Howard County.
21787 (Taneytown): 87% here; 13% in Frederick County.
21791 (Union Bridge): 39% here; 61% in Frederick County.
21797 (Lisbon): 32% here; 67% in Howard County and 1.3% in Montgomery County.

Cities and prefixes

By main city (the city, town or CDP each ZIP shares the most land with), the ones with the most are Eldersburg (3), Westminster (2), Green Valley (1), Hampstead (1), Lisbon (1), and Manchester (1); 10 places in all.

They start with 3 different three-digit prefixes, one per USPS sorting center: 210, 211, and 217.

Neighboring counties

Each one with its ZIP codes. Those without a page of their own open in the tool.

Tools for this county

ZIP codes by county or city The same ZIP codes on an interactive map, with the list as CSV or to copy County map with cities Its cities, towns and CDPs with their population ZIP codes in a radius The ZIP codes within 10 miles of its center, or any distance you like

Sources

U.S. Census Bureau, 2020 ZCTA to County, ZCTA to Place and ZCTA to Census Tract Relationship Files (and the 2022 County Subdivision to ZCTA file for Connecticut). Public domain.
U.S. Census Bureau, American Community Survey 2020–2024 5-year estimates, table B01003 (population of each ZIP code, census tract and Connecticut town). Public domain.
U.S. Census Bureau, Vintage 2025 Population Estimates (county population) and 2025 Gazetteer Files (land area and interior point of each ZIP code). Public domain.
U.S. Census Bureau, Cartographic Boundary Files: ZCTAs 2020 and counties 2025, 1:500,000; county adjacency file 2025. Public domain.

How we count. ZIP codes here are the Census Bureau’s ZIP Code Tabulation Areas (ZCTAs), the areas it draws to match USPS ZIP codes; ZIPs with no area of their own (PO boxes, single buildings) aren’t included. A ZIP can cross county lines: “Land in the county” is the exact share of its land inside, from the Census relationship files. “Residents in the county” is the whole ZIP for those entirely inside; for shared ones it’s an estimate, spreading the people of each census tract over the land it shares with the ZIP. Population: ACS 2020–2024. Methodology.

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