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/DC/HIGHEST-DENSITY

Most Densely Populated ZIP Codes in District of Columbia

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 20390 Washington District of Columbia 61,500
2 20052 Washington District of Columbia 60,667
3 20009 Washington District of Columbia 38,050
4 20010 Washington District of Columbia 31,968
5 20005 Washington District of Columbia 30,326
6 20001 Washington District of Columbia 21,796
7 20057 Washington District of Columbia 20,699
8 20037 Washington District of Columbia 17,973
9 20003 Washington District of Columbia 16,490
10 20036 Washington District of Columbia 14,169
11 20002 Washington District of Columbia 14,093
12 20011 Washington District of Columbia 12,574
13 20059 Washington District of Columbia 12,389
14 20020 Washington District of Columbia 11,525
15 20019 Washington District of Columbia 10,329
16 20017 Washington District of Columbia 9,545
17 20008 Washington District of Columbia 9,529
18 20004 Washington District of Columbia 9,438
19 20012 Washington District of Columbia 8,492
20 20007 Washington District of Columbia 7,962
21 20032 Washington District of Columbia 7,797
22 20064 Washington District of Columbia 7,472
23 20016 Washington District of Columbia 7,387
24 20024 Washington District of Columbia 7,242
25 20018 Washington District of Columbia 6,482
26 20015 Washington District of Columbia 4,503
27 20006 Washington District of Columbia 3,858
28 20373 Naval Anacost Annex District of Columbia 758
29 20319 Washington District of Columbia 168
30 20422 Washington District of Columbia 128
31 20317 Washington District of Columbia 43
32 20045 Washington District of Columbia 0
33 20204 Washington District of Columbia 0
34 20220 Washington District of Columbia 0
35 20230 Washington District of Columbia 0
36 20240 Washington District of Columbia 0
37 20245 Washington District of Columbia 0
38 20250 Washington District of Columbia 0
39 20260 Washington District of Columbia 0
40 20388 Washington Navy Yard District of Columbia 0
41 20408 Washington District of Columbia 0
42 20415 Washington District of Columbia 0
43 20418 Washington District of Columbia 0
44 20427 Washington District of Columbia 0
45 20431 Washington District of Columbia 0
46 20510 Washington District of Columbia 0
47 20515 Washington District of Columbia 0
48 20520 Washington District of Columbia 0
49 20530 Washington District of Columbia 0
50 20535 Washington District of Columbia 0

Showing the top 50 of 57 ZIP codes in District of Columbia that have this figure . 20390 ranks 1st at 61,500, against 0 in 50th place.

Other rankings for District of Columbia

Cite this page

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

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