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 — PREFIX/511

ZIP codes starting with 511

ZIP codes
9
States
IA
Largest city
Sioux City, IA
Population
89,735

The first three digits of a ZIP code identify a sectional center facility — the postal processing plant that sorts mail for the area. It is a mail-routing grouping, not an administrative boundary.

Every ZIP code in 511xx

ZIP codes starting with 511
ZIP City Type Population Median income Median home
51101 Sioux City , IA Standard 1,031 $15,300 —
51102 Sioux City , IA No street area — — —
51103 Sioux City , IA Standard 16,895 $58,197 $142,900
51104 Sioux City , IA Standard 23,197 $75,362 $211,100
51105 Sioux City , IA Standard 10,415 $51,786 $96,200
51106 Sioux City , IA Standard 28,592 $78,434 $200,200
51108 Sioux City , IA Standard 5,960 $81,205 $169,700
51109 Sioux City , IA Standard 3,606 $79,034 $130,900
51111 Sioux City , IA Standard 39 — —

Cite this page

zipcodes.pro. “ZIP codes starting with 511.” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/prefix/511

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