County ZIP codes · Iowa · FIPS 19037
Chickasaw County, IA ZIP Codes
Chickasaw County, Iowa has 10 ZIP codes (Census 2020 ZCTA-county file; GeoNames postal codes, October 2026): 9 residential and 1 for PO boxes or a single organization. 6 of the residential ones lie mainly in Chickasaw County and 3 mainly in a neighboring county; 8 cross the county line. Median household income ranges from $64,830 in 50616 (Charles City) to $94,904 in 52171 (Waucoma) (Census Bureau, ACS 2020-2024).
- ACS2020-24
- Census2020
Where are the ZIP codes of Chickasaw County?
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 $71,518 and $72,794.
They carry 9 postal town names.
Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates (B19013).
All 9 residential ZIP codes in Chickasaw County
6 ZIP codes lie mainly in Chickasaw County; 3 more reach into it from a neighboring county and follow the first table.
| In this county | ||||||
|---|---|---|---|---|---|---|
| 50659 | New Hampton | 5,688 | 37 | $78k | $207k | 100% |
| 50658 | Nashua | 2,450 | 31 | $72k | $155k | 55% |
| 50630 | Fredericksburg | 1,372 | 16 | $72k | $199k | 90% |
| 50645 | Ionia | 1,193 | 14 | $64k | $115k | 90% |
| 52154 | Lawler | 592 | 8 | $58k | $156k | 99% |
| 50603 | Alta Vista | 555 | 12 | $74k | $123k | 83% |
Partly in Chickasaw County
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?
8 ZIP codes of Chickasaw County extend into another county. A ZIP code follows mail routes, not county borders.
| ZIP | In Chickasaw | Elsewhere |
|---|---|---|
| 50616 | 6% | Floyd County 94% |
| 50674 | 6% | Bremer County 62%; Fayette County 32% |
| 50658 | 55% | Floyd County 34%; Butler County 7%; Bremer County 4% |
| 50630 | 90% | Bremer County 10% |
| 52171 | 31% | Fayette County 50%; Winneshiek County 18% |
| 50645 | 90% | Bremer County 7%; Floyd County 3% |
| 52154 | 99% | Howard County 1% |
| 50603 | 83% | Howard County 17% |
Source: U.S. Census Bureau, 2020 ZCTA-county relationship file (shares of land area).
PO Box and single-organization ZIP codes
| ZIP | Postal name |
|---|---|
| 50661 | North Washington |
Source: GeoNames postal codes (CC BY 4.0).
Which first three digits do Chickasaw County's ZIP codes use?
The first three digits of a ZIP code name the sectional center, the mail processing plant that sorts it. Chickasaw County's ZIP codes use 2 prefixes: 506 and 521.
Source: U.S. Postal Service, labeling list L005 (3-digit ZIP Code prefix groups, SCF sortation), effective October 1, 2026.