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-POPULATION

ZIP Codes With the Largest Population in Maryland

What this measures. Population of the Census tabulation area, ACS 5-year estimate. Source: Census American Community Survey, data release 2026-10-12.

# ZIP City County Population
1 20906 Silver Spring Montgomery 70,595
2 21234 Parkville Baltimore 66,334
3 20878 Gaithersburg Montgomery 66,115
4 21740 Hagerstown Washington 64,792
5 21117 Owings Mills Baltimore 62,816
6 20874 Germantown Montgomery 62,738
7 21122 Pasadena Anne Arundel 61,566
8 21222 Dundalk Baltimore 59,407
9 20904 Silver Spring Montgomery 58,646
10 21061 Glen Burnie Anne Arundel 57,230
11 20744 Fort Washington Prince George's 54,441
12 20772 Upper Marlboro Prince George's 54,319
13 20902 Silver Spring Montgomery 54,261
14 21215 Baltimore Baltimore city 52,229
15 20774 Upper Marlboro Prince George's 51,816
16 20854 Potomac Montgomery 50,498
17 21228 Catonsville Baltimore 50,492
18 20850 Rockville Montgomery 50,353
19 20783 Hyattsville Prince George's 50,333
20 21702 Frederick Frederick 49,605
21 21206 Baltimore Baltimore city 48,902
22 21043 Ellicott City Howard 48,525
23 20852 Rockville Montgomery 48,180
24 21224 Baltimore Baltimore city 47,465
25 21207 Gwynn Oak Baltimore 47,099
26 21229 Baltimore Baltimore city 46,679
27 20910 Silver Spring Montgomery 45,943
28 21921 Elkton Cecil 45,527
29 21044 Columbia Howard 44,114
30 21218 Baltimore Baltimore city 44,014
31 21221 Essex Baltimore 43,487
32 21042 Ellicott City Howard 43,327
33 21701 Frederick Frederick 43,048
34 21220 Middle River Baltimore 42,824
35 20706 Lanham Prince George's 42,612
36 21703 Frederick Frederick 41,960
37 20743 Capitol Heights Prince George's 41,093
38 21502 Cumberland Allegany 41,015
39 21804 Salisbury Wicomico 40,430
40 20748 Temple Hills Prince George's 40,338
41 20785 Hyattsville Prince George's 40,066
42 21045 Columbia Howard 40,034
43 21060 Glen Burnie Anne Arundel 39,730
44 21236 Nottingham Baltimore 39,514
45 21784 Sykesville Carroll 39,258
46 21093 Lutherville Timonium Baltimore 39,100
47 21157 Westminster Carroll 38,984
48 21014 Bel Air Harford 38,707
49 21401 Annapolis Anne Arundel 38,629
50 20877 Gaithersburg Montgomery 38,546

Showing the top 50 of 477 ZIP codes in Maryland that have this figure . 20906 ranks 1st at 70,595, against 38,546 in 50th place.

Other rankings for Maryland

Cite this page

zipcodes.pro. “ZIP Codes With the Largest Population in Maryland.” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/rankings/md/largest-population

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