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County ZIP codes · Iowa · FIPS 19143

Osceola County, IA ZIP Codes

Osceola County, Iowa has 8 ZIP codes (Census 2020 ZCTA-county file; GeoNames postal codes, October 2026), all residential. 5 of the residential ones lie mainly in Osceola County and 3 mainly in a neighboring county; 6 cross the county line. Median household income ranges from $64,375 in 51248 (Sanborn) to $72,426 in 51346 (Hartley) (Census Bureau, ACS 2020-2024).

  • ACS2020-24
  • Census2020

Where are the ZIP codes of Osceola County?

51232 · Ashton: $83k51243 · Little Rock: $84k51248 · Sanborn: $64k51249 · Sibley: $62k51345 · Harris: $54k51346 · Hartley: $72k51350 · Melvin: $77k51354 · Ocheyedan: $73k513465124951354512485123251345513505124351232 · Ashton: $83k51243 · Little Rock: $84k51248 · Sanborn: $64k51249 · Sibley: $62k51345 · Harris: $54k51346 · Hartley: $72k51350 · Melvin: $77k51354 · Ocheyedan: $73k513465124951354512485123251345513505124351232 · Ashton: $83k51243 · Little Rock: $84k51248 · Sanborn: $64k51249 · Sibley: $62k51345 · Harris: $54k51346 · Hartley: $72k51350 · Melvin: $77k51354 · Ocheyedan: $73k5134651249513545124851232513455135051243
The residential ZIP codes of Osceola 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?

They carry 8 postal town names: Sibley, Hartley, Sanborn, Ocheyedan, Little Rock, Ashton, Melvin, Harris.

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

All 8 residential ZIP codes in Osceola County

5 ZIP codes lie mainly in Osceola County; 3 more reach into it from a neighboring county and follow the first table.

Residential ZIP codes mainly in Osceola County, largest first; "In this county" is the share of the ZIP's land in the county
In this county
51249 Sibley 3,564 28 $62k $161k 100%
51354 Ocheyedan 965 11 $73k $115k 100%
51232 Ashton 658 11 $83k $108k 73%
51350 Melvin 383 9 $77k $79k 93%
51345 Harris 347 6 $54k $142k 97%

Partly in Osceola County

Residential ZIP codes mainly in another county that reach at least 1% into Osceola County, by their share here
In this county
51346 Hartley 2,247 15 $72k $157k 20%
51243 Little Rock 735 14 $84k $92k 14%
51248 Sanborn 1,534 19 $64k $173k 10%

Download the 8 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?

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

Share of each ZIP code's land in Osceola County and in the neighboring counties
ZIPIn OsceolaElsewhere
5134620%O'Brien County 71%; Clay County 8%
5124810%O'Brien County 90%
5124314%Lyon County 86%
5123273%Lyon County 26%; O'Brien County 2%
5135093%O'Brien County 7%
5134597%Dickinson County 3%

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

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

The first three digits of a ZIP code name the sectional center, the mail processing plant that sorts it. Osceola County's ZIP codes use 2 prefixes: 512 and 513.

Three-digit prefixes of Osceola 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 Osceola County's
PrefixSectional centerHereAll codes
512 Sioux Falls, SD (SCF 570) 4 20
513 Sioux Falls, SD (SCF 570) 4 23

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