First three digits · Iowa
ZIP Codes Starting with
53 ZIP codes start with 523, sorted at the Cedar Rapids, IA (SCF 522) sectional center (USPS labeling list L005, effective October 1, 2026) in Iowa: 53 residential ZIP codes across 12 counties (Census 2020 ZCTAs and GeoNames postal codes, October 2026).
What do the digits 523 mean?
The first digit, 5, is one of ten national areas (Iowa, Minnesota, Montana, North Dakota, South Dakota and Wisconsin). The first three, 523, route mail to a sectional center: USPS labeling list L005 (effective October 1, 2026) sends letters for 523 to the Cedar Rapids, IA (SCF 522) facility. The last two digits pick the delivery area. By residents, the largest town names among the 523 ZIP codes are Marion, North Liberty, Washington, Vinton, Solon and Monticello.
The same facility sorts 4 prefixes, 163 ZIP codes in all: 520, 522, 523, 524.
Where are the 523 ZIP codes?
Source: U.S. Census Bureau, 2020 ZCTA cartographic boundaries; ACS 2020-2024 5-year estimates (B19013).
All ZIP codes starting with 523
| County | ||||||
|---|---|---|---|---|---|---|
| 52301 | Marengo | Iowa County | 4,028 | 32 | $70k | $160k |
| 52302 | Marion | Linn County | 42,706 | 574 | $88k | $244k |
| 52305 | Martelle | Jones County | 913 | 34 | $95k | $165k |
| 52306 | Mechanicsville | Cedar County | 1,642 | 22 | $62k | $168k |
| 52307 | Middle Amana | Iowa County | 63 | 118 | $43k | – |
| 52308 | Millersburg | Iowa County | 129 | 1,057 | $80k | $107k |
| 52309 | Monmouth | Jackson County | 443 | 13 | $56k | $155k |
| 52310 | Monticello | Jones County | 6,450 | 44 | $86k | $196k |
| 52312 | Morley | Jones County | 46 | 639 | $37k | $84k |
| 52313 | Mount Auburn | Benton County | 480 | 16 | $91k | $208k |
| 52314 | Mount Vernon | Linn County | 6,200 | 105 | $109k | $265k |
| 52315 | Newhall | Benton County | 1,339 | 47 | $78k | $196k |
| 52316 | North English | Iowa County | 1,597 | 22 | $61k | $151k |
| 52317 | North Liberty | Johnson County | 23,097 | 672 | $105k | $323k |
| 52318 | Norway | Benton County | 1,099 | 31 | $86k | $188k |
| 52320 | Olin | Jones County | 1,425 | 25 | $62k | $131k |
| 52321 | Onslow | Jones County | 395 | 11 | $78k | $131k |
| 52322 | Oxford | Johnson County | 2,266 | 26 | $64k | $261k |
| 52323 | Oxford Junction | Jones County | 942 | 20 | $41k | $86k |
| 52324 | Palo | Linn County | 2,216 | 53 | $116k | $327k |
| 52325 | Parnell | Iowa County | 477 | 12 | $76k | – |
| 52326 | Quasqueton | Buchanan County | 694 | 700 | $76k | $144k |
| 52327 | Riverside | Washington County | 3,796 | 47 | $87k | $299k |
| 52328 | Robins | Linn County | 2,712 | 1,004 | $125k | $383k |
| 52329 | Rowley | Buchanan County | 671 | 13 | $58k | $171k |
| 52330 | Ryan | Delaware County | 940 | 20 | $87k | $261k |
| 52332 | Shellsburg | Benton County | 1,612 | 41 | $93k | $198k |
| 52333 | Solon | Johnson County | 7,295 | 85 | $119k | $367k |
| 52334 | South Amana | Iowa County | 181 | 13 | – | $173k |
| 52335 | South English | Keokuk County | 644 | 13 | $52k | $106k |
| 52336 | Springville | Linn County | 2,397 | 50 | $92k | $225k |
| 52337 | Stanwood | Cedar County | 729 | 24 | $67k | $160k |
| 52338 | Swisher | Johnson County | 3,934 | 118 | $120k | $393k |
| 52339 | Tama | Tama County | 4,326 | 44 | $68k | $121k |
| 52340 | Tiffin | Johnson County | 6,128 | 322 | $98k | $343k |
| 52341 | Toddville | Linn County | 1,378 | 102 | $91k | $372k |
| 52342 | Toledo | Tama County | 2,705 | 30 | $58k | $143k |
| 52344 | Troy Mills | Linn County | 67 | 7,444 | – | – |
| 52345 | Urbana | Benton County | 1,609 | 506 | $115k | $227k |
| 52346 | Van Horne | Benton County | 1,113 | 23 | $113k | $247k |
| 52347 | Victor | Iowa County | 1,386 | 22 | $79k | $145k |
| 52348 | Vining | Tama County | 66 | 228 | $73k | $91k |
| 52349 | Vinton | Benton County | 7,737 | 52 | $71k | $181k |
| 52351 | Walford | Benton County | 1,329 | 720 | $129k | $303k |
| 52352 | Walker | Linn County | 1,833 | 23 | $92k | $231k |
| 52353 | Washington | Washington County | 9,241 | 59 | $63k | $161k |
| 52354 | Watkins | Benton County | 420 | 14 | $113k | $166k |
| 52355 | Webster | Keokuk County | 283 | 8 | $64k | $110k |
| 52356 | Wellman | Washington County | 2,664 | 28 | $57k | $228k |
| 52358 | West Branch | Cedar County | 3,598 | 46 | $92k | $240k |
| 52359 | West Chester | Washington County | 308 | 22 | $68k | – |
| 52361 | Williamsburg | Iowa County | 4,582 | 35 | $61k | $211k |
| 52362 | Wyoming | Jones County | 816 | 15 | $73k | $136k |
Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates; GeoNames postal codes (CC BY 4.0) for codes without a residential area.