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/MOST-TAX-RETURNS

ZIP Codes With the Most Tax Returns Filed in Maryland

What this measures. Number of individual income tax returns filed. A rough proxy for how many households a ZIP code contains, available where census figures are not. Source: IRS Statistics of Income, ZIP code data, data release 2026-10-12.

# ZIP City County Returns filed
1 20906 Silver Spring Montgomery 39,320
2 21234 Parkville Baltimore 33,940
3 20878 Gaithersburg Montgomery 33,280
4 20874 Germantown Montgomery 32,360
5 21122 Pasadena Anne Arundel 31,960
6 21740 Hagerstown Washington 30,400
7 20904 Silver Spring Montgomery 30,000
8 21117 Owings Mills Baltimore 29,340
9 20774 Upper Marlboro Prince George's 28,800
10 20772 Upper Marlboro Prince George's 28,540
11 20744 Fort Washington Prince George's 28,340
12 21061 Glen Burnie Anne Arundel 27,990
13 21222 Dundalk Baltimore 27,830
14 20902 Silver Spring Montgomery 27,110
15 21224 Baltimore Baltimore city 27,080
16 20850 Rockville Montgomery 25,850
17 20852 Rockville Montgomery 24,830
18 20706 Lanham Prince George's 24,640
19 21228 Catonsville Baltimore 24,610
20 21702 Frederick Frederick 24,370
21 20783 Hyattsville Prince George's 23,670
22 20910 Silver Spring Montgomery 23,170
23 20854 Potomac Montgomery 23,150
24 21043 Ellicott City Howard 23,150
25 21207 Gwynn Oak Baltimore 23,120
26 21206 Baltimore Baltimore city 22,940
27 21044 Columbia Howard 22,840
28 21703 Frederick Frederick 22,810
29 21215 Baltimore Baltimore city 22,030
30 21220 Middle River Baltimore 22,000
31 21701 Frederick Frederick 21,520
32 21401 Annapolis Anne Arundel 21,170
33 20735 Clinton Prince George's 20,980
34 21221 Essex Baltimore 20,920
35 21236 Nottingham Baltimore 20,790
36 21921 Elkton Cecil 20,760
37 21042 Ellicott City Howard 20,610
38 20785 Hyattsville Prince George's 20,540
39 20707 Laurel Prince George's 20,490
40 21060 Glen Burnie Anne Arundel 20,240
41 20743 Capitol Heights Prince George's 19,960
42 20877 Gaithersburg Montgomery 19,900
43 21045 Columbia Howard 19,900
44 21093 Lutherville Timonium Baltimore 19,830
45 21229 Baltimore Baltimore city 19,820
46 21784 Sykesville Carroll 19,810
47 21113 Odenton Anne Arundel 19,710
48 20748 Temple Hills Prince George's 19,360
49 20747 District Heights Prince George's 19,240
50 21014 Bel Air Harford 19,180

Showing the top 50 of 403 ZIP codes in Maryland that have this figure . 20906 ranks 1st at 39,320, against 19,180 in 50th place.

Other rankings for Maryland

Cite this page

zipcodes.pro. “ZIP Codes With the Most Tax Returns Filed in Maryland.” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/rankings/md/most-tax-returns

Underlying data is public domain or openly licensed — sources, vintages and licences.