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/HIGHEST-DENSITY

Most Densely Populated ZIP Codes in Maryland

What this measures. People per square mile of land area. Source: Census American Community Survey and Gazetteer, data release 2026-10-12.

# ZIP City County People per sq mi
1 21252 Towson Baltimore 19,538
2 21231 Baltimore Baltimore city 17,265
3 21217 Baltimore Baltimore city 14,525
4 21201 Baltimore Baltimore city 14,415
5 20742 College Park Prince George's 13,509
6 20712 Mount Rainier Prince George's 13,100
7 21202 Baltimore Baltimore city 12,799
8 21250 Baltimore Baltimore 11,567
9 21218 Baltimore Baltimore city 10,167
10 20910 Silver Spring Montgomery 9,996
11 20912 Takoma Park Montgomery 9,611
12 21890 Westover Somerset 9,370
13 21239 Baltimore Baltimore city 9,330
14 21746 Hagerstown Washington 8,977
15 21216 Baltimore Baltimore city 8,912
16 20710 Bladensburg Prince George's 8,774
17 20783 Hyattsville Prince George's 8,620
18 20886 Montgomery Village Montgomery 8,464
19 21213 Baltimore Baltimore city 8,175
20 20784 Hyattsville Prince George's 8,172
21 20782 Hyattsville Prince George's 8,065
22 21229 Baltimore Baltimore city 7,864
23 20737 Riverdale Prince George's 7,737
24 21215 Baltimore Baltimore city 7,667
25 21214 Baltimore Baltimore city 7,549
26 21223 Baltimore Baltimore city 7,453
27 21212 Baltimore Baltimore city 7,408
28 20814 Bethesda Montgomery 7,355
29 20903 Silver Spring Montgomery 7,277
30 20902 Silver Spring Montgomery 7,174
31 20877 Gaithersburg Montgomery 6,842
32 20901 Silver Spring Montgomery 6,813
33 21206 Baltimore Baltimore city 6,742
34 21205 Baltimore Baltimore city 6,345
35 20852 Rockville Montgomery 5,967
36 20851 Rockville Montgomery 5,894
37 20815 Chevy Chase Montgomery 5,666
38 20906 Silver Spring Montgomery 5,544
39 20781 Hyattsville Prince George's 5,430
40 21225 Brooklyn Anne Arundel 5,272
41 21211 Baltimore Baltimore city 5,221
42 21230 Baltimore Baltimore city 5,220
43 21222 Dundalk Baltimore 5,165
44 20816 Bethesda Montgomery 5,090
45 21224 Baltimore Baltimore city 5,090
46 21234 Parkville Baltimore 4,967
47 20747 District Heights Prince George's 4,848
48 20895 Kensington Montgomery 4,709
49 21061 Glen Burnie Anne Arundel 4,694
50 21209 Baltimore Baltimore 4,665

Showing the top 50 of 477 ZIP codes in Maryland that have this figure . 21252 ranks 1st at 19,538, against 4,665 in 50th place.

Other rankings for Maryland

Cite this page

zipcodes.pro. “Most Densely Populated ZIP Codes in Maryland.” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/rankings/md/highest-density

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