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/MA/HIGHEST-DENSITY

Most Densely Populated ZIP Codes in Massachusetts

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 02113 Boston Suffolk 65,825
2 02111 Boston Suffolk 42,893
3 02115 Boston Suffolk 41,779
4 02116 Boston Suffolk 33,864
5 02114 Boston Suffolk 32,546
6 02215 Boston Suffolk 27,807
7 02118 Boston Suffolk 26,605
8 01063 Northampton Hampshire 25,818
9 02139 Cambridge Middlesex 25,795
10 02120 Roxbury Crossing Suffolk 24,690
11 02446 Brookline Norfolk 24,404
12 02141 Cambridge Middlesex 23,837
13 02144 Somerville Middlesex 23,304
14 02199 Boston Suffolk 22,667
15 02109 Boston Suffolk 21,247
16 01902 Lynn Essex 21,125
17 02145 Somerville Middlesex 19,766
18 02124 Dorchester Center Suffolk 18,941
19 02140 Cambridge Middlesex 18,311
20 02150 Chelsea Suffolk 18,025
21 02127 Boston Suffolk 17,866
22 01841 Lawrence Essex 17,341
23 02119 Roxbury Suffolk 16,952
24 01003 Amherst Hampshire 16,804
25 01840 Lawrence Essex 16,710
26 02135 Brighton Suffolk 16,596
27 02143 Somerville Middlesex 16,524
28 02125 Dorchester Suffolk 15,527
29 02121 Dorchester Suffolk 15,398
30 02142 Cambridge Middlesex 15,086
31 02129 Charlestown Suffolk 14,806
32 02149 Everett Middlesex 14,637
33 02126 Mattapan Suffolk 14,542
34 02134 Allston Suffolk 14,294
35 01610 Worcester Worcester 14,280
36 02138 Cambridge Middlesex 14,065
37 02108 Boston Suffolk 13,847
38 02122 Dorchester Suffolk 13,836
39 02110 Boston Suffolk 13,084
40 02148 Malden Middlesex 13,061
41 01850 Lowell Middlesex 13,035
42 02130 Jamaica Plain Suffolk 11,315
43 02152 Winthrop Suffolk 11,301
44 02131 Roslindale Suffolk 11,173
45 02723 Fall River Bristol 10,700
46 02151 Revere Suffolk 10,519
47 01851 Lowell Middlesex 10,345
48 02724 Fall River Bristol 10,275
49 01608 Worcester Worcester 10,232
50 02163 Boston Suffolk 9,929

Showing the top 50 of 539 ZIP codes in Massachusetts that have this figure . 02113 ranks 1st at 65,825, against 9,929 in 50th place.

Other rankings for Massachusetts

Cite this page

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

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