Every ZIP code in the United States, with weather, radar, trivia and the numbers behind it. Five digits since 1963!

ZIP stands for Zone Improvement Plan. The codes went live on July 1, 1963.The lowest ZIP code is 00501 — the IRS in Holtsville, New York.The highest ZIP code is 99950, in Ketchikan, Alaska.Type 07734 into a calculator and turn it upside down: hELLO. It is Keansburg, New Jersey.12345 belongs to one company: General Electric in Schenectady, New York.The first digit is a region: 0 is New England and New Jersey, 9 is the West Coast, Alaska and Hawaii.Mr. ZIP, the cartoon mailman, was the mascot that sold the idea to America.ZIP+4 arrived in 1983 and can narrow a ZIP down to one side of one block.A ZIP code is a mail route, not a place: plenty of them cross county and even state lines.Play ZIP Hunt: guess the secret ZIP code of the day in six tries.
zipcodes.pro — RANKINGS/MD/LARGEST-AREA

Largest ZIP Codes in Maryland by Land Area

What this measures. Land area of the Census tabulation area, in square miles. Water is excluded. Source: Census Gazetteer, data release 2026-10-12.

# ZIP City County Land area
1 21550 Oakland Garrett 205.47 sq mi
2 21613 Cambridge Dorchester 153.67 sq mi
3 21863 Snow Hill Worcester 122.54 sq mi
4 21620 Chestertown Kent 118.70 sq mi
5 21853 Princess Anne Somerset 114.78 sq mi
6 21617 Centreville Queen Anne's 108.48 sq mi
7 21601 Easton Talbot 107.07 sq mi
8 21851 Pocomoke City Worcester 103.63 sq mi
9 21561 Swanton Garrett 101.85 sq mi
10 21811 Berlin Worcester 101.50 sq mi
11 21555 Oldtown Allegany 98.29 sq mi
12 21536 Grantsville Garrett 97.88 sq mi
13 20659 Mechanicsville St. Mary's 97.01 sq mi
14 21921 Elkton Cecil 94.73 sq mi
15 21502 Cumberland Allegany 92.09 sq mi
16 21771 Mount Airy Frederick 89.52 sq mi
17 21869 Vienna Dorchester 86.94 sq mi
18 21629 Denton Caroline 83.62 sq mi
19 20646 La Plata Charles 79.77 sq mi
20 21632 Federalsburg Caroline 77.82 sq mi
21 21157 Westminster Carroll 77.69 sq mi
22 21532 Frostburg Allegany 74.13 sq mi
23 21158 Westminster Carroll 73.32 sq mi
24 20772 Upper Marlboro Prince George's 72.47 sq mi
25 20613 Brandywine Prince George's 72.41 sq mi
26 21740 Hagerstown Washington 70.88 sq mi
27 21804 Salisbury Wicomico 68.56 sq mi
28 21871 Westover Somerset 67.12 sq mi
29 21788 Thurmont Frederick 65.45 sq mi
30 21622 Church Creek Dorchester 64.37 sq mi
31 21750 Hancock Washington 61.64 sq mi
32 20650 Leonardtown St. Mary's 61.42 sq mi
33 21531 Friendsville Garrett 61.16 sq mi
34 21787 Taneytown Carroll 61.08 sq mi
35 21530 Flintstone Allegany 60.89 sq mi
36 21722 Clear Spring Washington 56.92 sq mi
37 21520 Accident Garrett 56.69 sq mi
38 20662 Nanjemoy Charles 56.41 sq mi
39 21136 Reisterstown Baltimore 56.20 sq mi
40 21784 Sykesville Carroll 56.13 sq mi
41 20842 Dickerson Montgomery 55.65 sq mi
42 21838 Marion Station Somerset 54.85 sq mi
43 21655 Preston Caroline 52.72 sq mi
44 21673 Trappe Talbot 51.80 sq mi
45 21901 North East Cecil 48.55 sq mi
46 21161 White Hall Harford 48.52 sq mi
47 20601 Waldorf Charles 47.83 sq mi
48 21783 Smithsburg Washington 47.60 sq mi
49 21742 Hagerstown Washington 46.50 sq mi
50 21643 Hurlock Dorchester 46.18 sq mi

Showing the top 50 of 477 ZIP codes in Maryland that have this figure and meet the threshold above. 21550 ranks 1st at 205.47 sq mi, against 46.18 sq mi in 50th place.

Other rankings for Maryland

Cite this page

zipcodes.pro. “Largest ZIP Codes in Maryland by Land Area.” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/rankings/md/largest-area

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