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/IL/HIGHEST-DENSITY

Most Densely Populated ZIP Codes in Illinois

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 60611 Chicago Cook 47,547
2 60654 Chicago Cook 47,519
3 60610 Chicago Cook 40,362
4 60601 Chicago Cook 39,165
5 60661 Chicago Cook 37,248
6 60660 Chicago Cook 33,535
7 60657 Chicago Cook 33,059
8 60626 Chicago Cook 28,941
9 60640 Chicago Cook 27,719
10 60605 Chicago Cook 25,322
11 60613 Chicago Cook 22,442
12 60614 Chicago Cook 21,941
13 60622 Chicago Cook 21,844
14 60645 Chicago Cook 21,657
15 60647 Chicago Cook 21,385
16 60625 Chicago Cook 20,399
17 60615 Chicago Cook 19,632
18 61402 Galesburg Knox 19,554
19 60618 Chicago Cook 18,402
20 60651 Chicago Cook 18,289
21 60602 Chicago Cook 18,049
22 60301 Oak Park Cook 17,821
23 60659 Chicago Cook 17,681
24 60641 Chicago Cook 17,108
25 60639 Chicago Cook 16,977
26 60606 Chicago Cook 16,552
27 60629 Chicago Cook 15,370
28 60623 Chicago Cook 15,116
29 60616 Chicago Cook 14,292
30 60653 Chicago Cook 14,145
31 60607 Chicago Cook 14,004
32 60644 Chicago Cook 13,446
33 60649 Chicago Cook 13,275
34 60165 Stone Park Cook 13,105
35 60642 Chicago Cook 13,063
36 60608 Chicago Cook 12,924
37 60632 Chicago Cook 11,962
38 60630 Chicago Cook 11,703
39 60637 Chicago Cook 11,643
40 60804 Cicero Cook 11,637
41 60707 Elmwood Park Cook 11,491
42 60302 Oak Park Cook 11,121
43 60402 Berwyn Cook 11,109
44 60304 Oak Park Cook 10,939
45 60603 Chicago Cook 10,908
46 60202 Evanston Cook 10,586
47 60634 Chicago Cook 10,393
48 60624 Chicago Cook 9,942
49 60619 Chicago Cook 9,718
50 60201 Evanston Cook 9,697

Showing the top 50 of 1,396 ZIP codes in Illinois that have this figure . 60611 ranks 1st at 47,547, against 9,697 in 50th place.

Other rankings for Illinois

Cite this page

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

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