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County ZIP codes · Iowa · FIPS 19075

Grundy County, IA ZIP Codes

Grundy County, Iowa has 17 ZIP codes (Census 2020 ZCTA-county file; GeoNames postal codes, October 2026), all residential. 9 of the residential ones lie mainly in Grundy County and 8 mainly in a neighboring county; 11 cross the county line. Median household income ranges from $66,250 in 50601 (Ackley) to $125,804 in 50643 (Hudson) (Census Bureau, ACS 2020-2024).

  • ACS2020-24
  • Census2020

Where are the ZIP codes of Grundy County?

50601 · Ackley: $66k50604 · Aplington: $67k50609 · Beaman: $90k50613 · Cedar Falls: $79k50621 · Conrad: $88k50624 · Dike: $97k50627 · Eldora: $75k50638 · Grundy Center: $85k50642 · Holland: $109k50643 · Hudson: $126k50657 · Morrison: $66k50660 · New Hartford: $96k50665 · Parkersburg: $76k50669 · Reinbeck: $82k50672 · Steamboat Rock: $73k50673 · Stout: $67k50680 · Wellsburg: $76k50601506135062750669506385066550604506245068050643506215067250660506095064250601 · Ackley: $66k50604 · Aplington: $67k50609 · Beaman: $90k50613 · Cedar Falls: $79k50621 · Conrad: $88k50624 · Dike: $97k50627 · Eldora: $75k50638 · Grundy Center: $85k50642 · Holland: $109k50643 · Hudson: $126k50657 · Morrison: $66k50660 · New Hartford: $96k50665 · Parkersburg: $76k50669 · Reinbeck: $82k50672 · Steamboat Rock: $73k50673 · Stout: $67k50680 · Wellsburg: $76k50601506135062750669506385066550604506245068050643506215067250660506095064250601 · Ackley: $66k50604 · Aplington: $67k50609 · Beaman: $90k50613 · Cedar Falls: $79k50621 · Conrad: $88k50624 · Dike: $97k50627 · Eldora: $75k50638 · Grundy Center: $85k50642 · Holland: $109k50643 · Hudson: $126k50657 · Morrison: $66k50660 · New Hartford: $96k50665 · Parkersburg: $76k50669 · Reinbeck: $82k50672 · Steamboat Rock: $73k50673 · Stout: $67k50680 · Wellsburg: $76k50601506135062750669506385066550604506245068050643506215067250660
The residential ZIP codes of Grundy County (whole outlines, including the parts in neighboring counties), shaded by median household income in national fifths (ACS 2020-2024). <$54.1k$98.1k+no figure

Source: U.S. Census Bureau, 2020 ZCTA cartographic boundaries; ACS 2020-2024 5-year estimates (B19013).

How different are its ZIP codes?

The middle half of its ranked ZIP codes (1,000+ people living in households) report median household incomes between $74,536 and $88,077.

They carry 17 postal town names.

Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates (B19013).

All 17 residential ZIP codes in Grundy County

9 ZIP codes lie mainly in Grundy County; 8 more reach into it from a neighboring county and follow the first table.

Residential ZIP codes mainly in Grundy County, largest first; "In this county" is the share of the ZIP's land in the county
In this county
50638 Grundy Center 3,441 37 $85k $185k 100%
50669 Reinbeck 2,439 25 $82k $183k 69%
50624 Dike 1,855 36 $97k $260k 100%
50621 Conrad 1,601 25 $88k $215k 84%
50680 Wellsburg 1,027 18 $76k $141k 99%
50642 Holland 577 18 $109k $179k 100%
50609 Beaman 377 11 $90k $242k 66%
50673 Stout 250 1,479 $67k $122k 100%
50657 Morrison 96 636 $66k $95k 100%

Partly in Grundy County

Residential ZIP codes mainly in another county that reach at least 1% into Grundy County, by their share here
In this county
50665 Parkersburg 2,693 27 $76k $218k 36%
50660 New Hartford 1,143 33 $96k $191k 21%
50604 Aplington 1,590 22 $67k $168k 20%
50627 Eldora 3,276 31 $75k $132k 17%
50601 Ackley 2,299 16 $66k $127k 16%
50613 Cedar Falls 43,867 344 $79k $271k 15%
50643 Hudson 3,027 53 $126k $244k 9%
50672 Steamboat Rock 611 16 $73k $159k 9%

Download the 17 ZIP codes as CSV

Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates; county shares by land area (Census 2020 ZCTA-county relationship file).

Which ZIP codes cross the county line?

12 ZIP codes of Grundy County extend into another county. A ZIP code follows mail routes, not county borders.

Share of each ZIP code's land in Grundy County and in the neighboring counties
ZIPIn GrundyElsewhere
5061315%Black Hawk County 81%; Butler County 4%
5062717%Hardin County 83%
506439%Black Hawk County 91%
5066536%Butler County 64%
5066969%Tama County 30%; Black Hawk County 1%
5060116%Franklin County 36%; Hardin County 30%; Butler County 18%
5062184%Marshall County 16%
5060420%Butler County 80%
5066021%Butler County 79%
5068099%
506729%Hardin County 91%
5060966%Marshall County 31%; Tama County 3%

Source: U.S. Census Bureau, 2020 ZCTA-county relationship file (shares of land area).

Which first three digits do Grundy County's ZIP codes use?

The first three digits of a ZIP code name the sectional center, the mail processing plant that sorts it. Every ZIP code of Grundy County starts with 506.

Three-digit prefixes of Grundy County's ZIP codes, the sectional center for each (USPS labeling list L005, effective October 1, 2026) and how many of the prefix's codes are Grundy County's
PrefixSectional centerHereAll codes
506 Waterloo, IA (SCF 506) 17 70

Source: U.S. Postal Service, labeling list L005 (3-digit ZIP Code prefix groups, SCF sortation), effective October 1, 2026.