First three digits · Iowa
ZIP Codes Starting with
70 ZIP codes start with 506, sorted at the Waterloo, IA (SCF 506) sectional center (USPS labeling list L005, effective October 1, 2026) in Iowa: 68 residential ZIP codes across 12 counties and 2 PO Box or single-organization codes (Census 2020 ZCTAs and GeoNames postal codes, October 2026).
What do the digits 506 mean?
The first digit, 5, is one of ten national areas (Iowa, Minnesota, Montana, North Dakota, South Dakota and Wisconsin). The first three, 506, route mail to a sectional center: USPS labeling list L005 (effective October 1, 2026) sends letters for 506 to the Waterloo, IA (SCF 506) facility. The last two digits pick the delivery area. By residents, the largest town names among the 506 ZIP codes are Cedar Falls, Waverly, Charles City, Independence, Oelwein and New Hampton.
The same facility sorts 4 prefixes, 165 ZIP codes in all: 504, 506, 507, 521.
Where are the 506 ZIP codes?
Source: U.S. Census Bureau, 2020 ZCTA cartographic boundaries; ACS 2020-2024 5-year estimates (B19013).
All ZIP codes starting with 506
| County | ||||||
|---|---|---|---|---|---|---|
| 50601 | Ackley | Franklin County | 2,299 | 16 | $66k | $127k |
| 50602 | Allison | Butler County | 1,254 | 16 | $67k | $118k |
| 50603 | Alta Vista | Chickasaw County | 555 | 12 | $74k | $123k |
| 50604 | Aplington | Butler County | 1,590 | 22 | $67k | $168k |
| 50605 | Aredale | Franklin County | 63 | 4 | $23k | $69k |
| 50606 | Arlington | Fayette County | 803 | 12 | $61k | $130k |
| 50607 | Aurora | Buchanan County | 403 | 8 | $55k | $143k |
| 50608 | Austinville | Butler County | 24 | 108 | – | – |
| 50609 | Beaman | Grundy County | 377 | 11 | $90k | $242k |
| 50611 | Bristow | Butler County | 364 | 12 | $84k | $93k |
| 50612 | Buckingham | Tama County | 369 | 13 | $100k | $292k |
| 50613 | Cedar Falls | Black Hawk County | 43,867 | 344 | $79k | $271k |
| 50614 | Cedar Falls | Black Hawk County | PO Box or unique | – | – | – |
| 50616 | Charles City | Floyd County | 9,358 | 53 | $65k | $141k |
| 50619 | Clarksville | Butler County | 2,150 | 26 | $84k | $163k |
| 50620 | Colwell | Floyd County | 36 | 248 | – | $103k |
| 50621 | Conrad | Grundy County | 1,601 | 25 | $88k | $215k |
| 50622 | Denver | Bremer County | 3,549 | 138 | $95k | $254k |
| 50623 | Dewar | Black Hawk County | 153 | 74 | $94k | $171k |
| 50624 | Dike | Grundy County | 1,855 | 36 | $97k | $260k |
| 50625 | Dumont | Butler County | 930 | 15 | $64k | $87k |
| 50626 | Dunkerton | Black Hawk County | 1,468 | 29 | $84k | $209k |
| 50627 | Eldora | Hardin County | 3,276 | 31 | $75k | $132k |
| 50628 | Elma | Howard County | 1,423 | 13 | $69k | $154k |
| 50629 | Fairbank | Buchanan County | 2,082 | 28 | $103k | $207k |
| 50630 | Fredericksburg | Chickasaw County | 1,372 | 16 | $72k | $199k |
| 50631 | Frederika | Bremer County | 225 | 1,216 | $59k | $99k |
| 50632 | Garwin | Tama County | 1,201 | 28 | $72k | $133k |
| 50633 | Geneva | Franklin County | 423 | 10 | $72k | $96k |
| 50634 | Gilbertville | Black Hawk County | 761 | 2,126 | $80k | $197k |
| 50635 | Gladbrook | Tama County | 1,423 | 17 | $81k | $155k |
| 50636 | Greene | Butler County | 2,186 | 19 | $70k | $155k |
| 50638 | Grundy Center | Grundy County | 3,441 | 37 | $85k | $185k |
| 50641 | Hazleton | Buchanan County | 1,950 | 43 | $67k | $156k |
| 50642 | Holland | Grundy County | 577 | 18 | $109k | $179k |
| 50643 | Hudson | Black Hawk County | 3,027 | 53 | $126k | $244k |
| 50644 | Independence | Buchanan County | 8,419 | 58 | $80k | $187k |
| 50645 | Ionia | Chickasaw County | 1,193 | 14 | $64k | $115k |
| 50647 | Janesville | Bremer County | 1,978 | 65 | $104k | $314k |
| 50648 | Jesup | Black Hawk County | 4,269 | 51 | $95k | $226k |
| 50649 | Kesley | Butler County | 12 | 414 | – | – |
| 50650 | Lamont | Buchanan County | 648 | 16 | $58k | $121k |
| 50651 | La Porte City | Black Hawk County | 3,147 | 27 | $88k | $188k |
| 50652 | Lincoln | Tama County | 113 | 303 | $65k | $98k |
| 50653 | Marble Rock | Floyd County | 486 | 9 | $79k | $163k |
| 50654 | Masonville | Buchanan County | 275 | 5 | $53k | $124k |
| 50655 | Maynard | Fayette County | 739 | 21 | $59k | $141k |
| 50657 | Morrison | Grundy County | 96 | 636 | $66k | $95k |
| 50658 | Nashua | Chickasaw County | 2,450 | 31 | $72k | $155k |
| 50659 | New Hampton | Chickasaw County | 5,688 | 37 | $78k | $207k |
| 50660 | New Hartford | Butler County | 1,143 | 33 | $96k | $191k |
| 50661 | North Washington | Chickasaw County | PO Box or unique | – | – | – |
| 50662 | Oelwein | Fayette County | 6,576 | 93 | $49k | $108k |
| 50664 | Oran | Fayette County | 63 | 67 | $52k | $157k |
| 50665 | Parkersburg | Butler County | 2,693 | 27 | $76k | $218k |
| 50666 | Plainfield | Bremer County | 753 | 15 | $80k | $204k |
| 50667 | Raymond | Black Hawk County | 899 | 473 | $77k | $223k |
| 50668 | Readlyn | Bremer County | 1,216 | 36 | $86k | $174k |
| 50669 | Reinbeck | Grundy County | 2,439 | 25 | $82k | $183k |
| 50670 | Shell Rock | Butler County | 2,270 | 41 | $85k | $172k |
| 50671 | Stanley | Fayette County | 182 | 8 | $57k | $108k |
| 50672 | Steamboat Rock | Hardin County | 611 | 16 | $73k | $159k |
| 50673 | Stout | Grundy County | 250 | 1,479 | $67k | $122k |
| 50674 | Sumner | Bremer County | 3,446 | 22 | $73k | $174k |
| 50675 | Traer | Tama County | 2,198 | 20 | $76k | $157k |
| 50676 | Tripoli | Bremer County | 2,017 | 36 | $87k | $155k |
| 50677 | Waverly | Bremer County | 12,673 | 99 | $86k | $233k |
| 50680 | Wellsburg | Grundy County | 1,027 | 18 | $76k | $141k |
| 50681 | Westgate | Fayette County | 481 | 20 | $73k | $113k |
| 50682 | Winthrop | Buchanan County | 1,692 | 20 | $89k | $184k |
Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates; GeoNames postal codes (CC BY 4.0) for codes without a residential area.