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/DE/MOST-TAX-RETURNS

ZIP Codes With the Most Tax Returns Filed in Delaware

What this measures. Number of individual income tax returns filed. A rough proxy for how many households a ZIP code contains, available where census figures are not. Source: IRS Statistics of Income, ZIP code data, data release 2026-10-12.

# ZIP City County Returns filed
1 19720 New Castle New Castle 29,640
2 19702 Newark New Castle 26,920
3 19709 Middletown New Castle 25,920
4 19711 Newark New Castle 22,380
5 19701 Bear New Castle 21,670
6 19808 Wilmington New Castle 20,260
7 19805 Wilmington New Castle 18,700
8 19966 Millsboro Sussex 18,460
9 19958 Lewes Sussex 17,860
10 19904 Dover Kent 17,590
11 19901 Dover Kent 15,870
12 19713 Newark New Castle 15,650
13 19977 Smyrna Kent 13,150
14 19810 Wilmington New Castle 12,920
15 19973 Seaford Sussex 12,730
16 19802 Wilmington New Castle 11,290
17 19803 Wilmington New Castle 11,140
18 19963 Milford Sussex 11,090
19 19947 Georgetown Sussex 9,780
20 19804 Wilmington New Castle 9,690
21 19971 Rehoboth Beach Sussex 9,020
22 19707 Hockessin New Castle 8,500
23 19968 Milton Sussex 8,280
24 19703 Claymont New Castle 7,900
25 19956 Laurel Sussex 7,830
26 19809 Wilmington New Castle 7,330
27 19934 Camden Wyoming Kent 7,190
28 19801 Wilmington New Castle 6,970
29 19734 Townsend New Castle 6,830
30 19962 Magnolia Kent 6,580
31 19943 Felton Kent 6,570
32 19975 Selbyville Sussex 6,020
33 19806 Wilmington New Castle 5,400
34 19970 Ocean View Sussex 5,310
35 19952 Harrington Kent 5,120
36 19933 Bridgeville Sussex 5,070
37 19938 Clayton Kent 4,970
38 19945 Frankford Sussex 4,870
39 19807 Wilmington New Castle 4,630
40 19939 Dagsboro Sussex 4,120
41 19960 Lincoln Sussex 3,510
42 19950 Greenwood Sussex 3,470
43 19940 Delmar Sussex 3,130
44 19946 Frederica Kent 2,360
45 19953 Hartly Kent 2,120
46 19930 Bethany Beach Sussex 1,590
47 19941 Ellendale Sussex 1,510
48 19951 Harbeson Sussex 1,370
49 19967 Millville Sussex 1,320
50 19954 Houston Kent 830

Showing the top 50 of 55 ZIP codes in Delaware that have this figure . 19720 ranks 1st at 29,640, against 830 in 50th place.

Other rankings for Delaware

Cite this page

zipcodes.pro. “ZIP Codes With the Most Tax Returns Filed in Delaware.” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/rankings/de/most-tax-returns

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