County ZIP codes · Iowa · FIPS 19167
Sioux County, IA ZIP Codes
Sioux County, Iowa has 19 ZIP codes (Census 2020 ZCTA-county file; GeoNames postal codes, October 2026), all residential. 13 of the residential ones lie mainly in Sioux County and 6 mainly in a neighboring county; 12 cross the county line. Median household income ranges from $68,799 in 51201 (Sheldon) to $101,250 in 51003 (Alton) (Census Bureau, ACS 2020-2024).
- ACS2020-24
- Census2020
Where are the ZIP codes of Sioux 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 $76,525 and $92,500.
They carry 19 postal town names.
Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates (B19013).
All 19 residential ZIP codes in Sioux County
13 ZIP codes lie mainly in Sioux County; 6 more reach into it from a neighboring county and follow the first table.
| In this county | ||||||
|---|---|---|---|---|---|---|
| 51250 | Sioux Center | 9,970 | 136 | $94k | $294k | 100% |
| 51041 | Orange City | 7,324 | 103 | $84k | $277k | 100% |
| 51201 | Sheldon | 6,430 | 56 | $69k | $198k | 49% |
| 51247 | Rock Valley | 5,094 | 45 | $78k | $263k | 95% |
| 51023 | Hawarden | 3,473 | 29 | $80k | $173k | 70% |
| 51239 | Hull | 2,876 | 43 | $78k | $237k | 93% |
| 51003 | Alton | 1,938 | 36 | $101k | $233k | 100% |
| 51238 | Hospers | 1,502 | 31 | $74k | $183k | 68% |
| 51027 | Ireton | 1,280 | 14 | $101k | $227k | 84% |
| 51234 | Boyden | 1,172 | 24 | $84k | $212k | 100% |
| 51036 | Maurice | 445 | 10 | $123k | $249k | 100% |
| 51244 | Matlock | 144 | 381 | $83k | $95k | 100% |
| 51011 | Chatsworth | 54 | 129 | $44k | – | 100% |
Partly in Sioux County
| In this county | ||||||
|---|---|---|---|---|---|---|
| 51022 | Granville | 960 | 13 | $97k | $175k | 40% |
| 51240 | Inwood | 1,914 | 19 | $84k | $233k | 15% |
| 57034 | Hudson | 661 | 9 | $90k | $194k | 8% |
| 51235 | Doon | 1,007 | 19 | $71k | $241k | 3% |
| 51050 | Remsen | 2,962 | 21 | $93k | $220k | 1% |
| 51031 | Le Mars | 12,808 | 55 | $77k | $223k | 1% |
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 Sioux County extend into another county. A ZIP code follows mail routes, not county borders.
| ZIP | In Sioux | Elsewhere |
|---|---|---|
| 51031 | 1% | Plymouth County 99% |
| 51201 | 49% | O'Brien County 49%; Lyon County 2% |
| 51247 | 95% | Lyon County 5% |
| 51023 | 70% | Union County 30% |
| 51050 | 1% | Plymouth County 99% |
| 51239 | 93% | Lyon County 7% |
| 51240 | 15% | Lyon County 85% |
| 51238 | 68% | O'Brien County 32% |
| 51027 | 84% | Plymouth County 16% |
| 51235 | 3% | Lyon County 97% |
| 51022 | 40% | O'Brien County 58%; Plymouth County 3% |
| 57034 | 8% | Lincoln County 84%; Union County 9% |
Source: U.S. Census Bureau, 2020 ZCTA-county relationship file (shares of land area).
Which first three digits do Sioux County's ZIP codes use?
The first three digits of a ZIP code name the sectional center, the mail processing plant that sorts it. Sioux County's ZIP codes use 3 prefixes: 510, 512 and 570.
| Prefix | Sectional center | Here | All codes |
|---|---|---|---|
| 510 | Sioux Falls, SD (SCF 570) | 9 | 55 |
| 512 | Sioux Falls, SD (SCF 570) | 9 | 20 |
| 570 | Sioux Falls, SD (SCF 570) | 1 | 69 |
Source: U.S. Postal Service, labeling list L005 (3-digit ZIP Code prefix groups, SCF sortation), effective October 1, 2026.