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/PA/HIGHEST-DENSITY

Most Densely Populated ZIP Codes in Pennsylvania

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 15282 Pittsburgh Allegheny 43,075
2 19103 Philadelphia Philadelphia 40,155
3 19545 New Berlinville Berks 39,455
4 19102 Philadelphia Philadelphia 33,128
5 16654 Huntingdon Huntingdon 29,781
6 19147 Philadelphia Philadelphia 29,674
7 19107 Philadelphia Philadelphia 27,252
8 19139 Philadelphia Philadelphia 24,358
9 19130 Philadelphia Philadelphia 24,346
10 19149 Philadelphia Philadelphia 23,843
11 19146 Philadelphia Philadelphia 23,816
12 19108 Philadelphia Philadelphia 22,000
13 19120 Philadelphia Philadelphia 20,553
14 19143 Philadelphia Philadelphia 20,081
15 18101 Allentown Lehigh 19,935
16 19122 Philadelphia Philadelphia 19,674
17 19133 Philadelphia Philadelphia 19,380
18 16802 University Park Centre 19,337
19 19125 Philadelphia Philadelphia 18,595
20 19141 Philadelphia Philadelphia 18,559
21 19104 Philadelphia Philadelphia 18,024
22 19121 Philadelphia Philadelphia 17,564
23 19138 Philadelphia Philadelphia 17,472
24 19106 Philadelphia Philadelphia 17,173
25 18102 Allentown Lehigh 17,103
26 19140 Philadelphia Philadelphia 16,937
27 19142 Philadelphia Philadelphia 16,512
28 19150 Philadelphia Philadelphia 16,433
29 19082 Upper Darby Delaware 16,132
30 19383 West Chester Chester 15,676
31 19123 Philadelphia Philadelphia 15,608
32 19134 Philadelphia Philadelphia 15,553
33 19132 Philadelphia Philadelphia 15,323
34 19135 Philadelphia Philadelphia 14,924
35 19126 Philadelphia Philadelphia 14,692
36 19144 Philadelphia Philadelphia 14,097
37 15705 Indiana Indiana 13,906
38 15232 Pittsburgh Allegheny 13,874
39 19151 Philadelphia Philadelphia 13,867
40 19124 Philadelphia Philadelphia 13,801
41 19111 Philadelphia Philadelphia 13,678
42 17401 York York 12,497
43 15213 Pittsburgh Allegheny 12,486
44 19152 Philadelphia Philadelphia 12,476
45 15510 Somerset Somerset 12,103
46 19604 Reading Berks 12,079
47 19148 Philadelphia Philadelphia 11,906
48 16172 New Wilmington Lawrence 11,843
49 19023 Darby Delaware 11,316
50 18046 East Texas Lehigh 11,167

Showing the top 50 of 1,833 ZIP codes in Pennsylvania that have this figure . 15282 ranks 1st at 43,075, against 11,167 in 50th place.

Other rankings for Pennsylvania

Cite this page

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

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