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/521

ZIP codes starting with 521

ZIP codes
33
States
IA
Largest city
Decorah, IA
Population
56,891

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 521xx

ZIP codes starting with 521
ZIP City Type Population Median income Median home
52101 Decorah , IA Standard 12,706 $73,484 $273,200
52132 Calmar , IA Standard 1,759 $100,559 $231,600
52133 Castalia , IA Standard 673 $76,250 $246,100
52134 Chester , IA Standard 223 $63,125 $208,300
52135 Clermont , IA Standard 834 $88,438 $121,400
52136 Cresco , IA Standard 5,840 $70,778 $161,100
52140 Dorchester , IA Standard 671 $72,188 $208,300
52141 Elgin , IA Standard 1,259 $64,647 $115,500
52142 Fayette , IA Standard 1,890 $56,875 $162,500
52144 Fort Atkinson , IA Standard 1,075 $84,609 $217,500
52146 Harpers Ferry , IA Standard 752 $61,750 $234,700
52147 Hawkeye , IA Standard 911 $77,083 $162,900
52149 Highlandville , IA No street area — — —
52151 Lansing , IA Standard 1,886 $69,938 $177,500
52154 Lawler , IA Standard 592 $58,393 $156,100
52155 Lime Springs , IA Standard 1,110 $57,917 $116,500
52156 Luana , IA Standard 769 $99,554 $225,700
52157 Mc Gregor , IA Standard 1,451 $52,625 $193,500
52158 Marquette , IA Standard 290 $47,188 $161,300
52159 Monona , IA Standard 2,398 $74,259 $165,400
52160 New Albin , IA Standard 818 $85,204 $211,200
52161 Ossian , IA Standard 1,532 $87,870 $171,400
52162 Postville , IA Standard 3,744 $64,125 $133,100
52163 Protivin , IA Standard 333 $78,194 $115,000
52164 Randalia , IA Standard 187 $48,375 $137,100
52165 Ridgeway , IA Standard 1,098 $85,227 $292,200
52166 Saint Lucas , IA Standard 137 $110,938 $146,900
52168 Spillville , IA Standard 356 $54,375 $157,500
52169 Wadena , IA Standard 367 $52,321 $112,900
52170 Waterville , IA Standard 555 $72,788 $222,700
52171 Waucoma , IA Standard 1,314 $94,904 $192,100
52172 Waukon , IA Standard 5,877 $68,875 $166,100
52175 West Union , IA Standard 3,484 $59,800 $160,600

Cite this page

zipcodes.pro. “ZIP codes starting with 521.” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/prefix/521

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