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County · code 19167

Sioux CountyIowa

Sioux County is a county in northwestern Iowa with its seat in Orange City. It was created in 1851 from Polk County.

  • Founded1851
  • County seatOrange City
  • Named forSioux
  • Land area768 sq mi + 1.1 sq mi water
  • Population35,872 2020 Census
  • Parcels mapped30,725 checked 15 October 2026
Open the free map Click any parcel in Sioux County: acreage, parcel id, address and who publishes the map. No sign-in.

Updated

LyonPlymouthUnion, SDO'BrienLincoln, SD Orange City Census outline · seat marked

Where it is

Sioux on the map of Iowa

Iowa has 99 counties and county equivalents, each with its own records office. Shapes with a page are links.

Adair CountyAdams CountyAllamakee CountyAppanoose CountyAudubon CountyBenton CountyBlack Hawk CountyBoone CountyBremer CountyBuchanan CountyBuena Vista CountyButler CountyCalhoun CountyCarroll CountyCass CountyCedar CountyCerro Gordo CountyCherokee CountyChickasaw CountyClarke CountyClay CountyClayton CountyClinton CountyCrawford CountyDallas CountyDavis CountyDecatur CountyDelaware CountyDes Moines CountyDickinson CountyDubuque CountyEmmet CountyFayette CountyFloyd CountyFranklin CountyFremont CountyGreene CountyGrundy CountyGuthrie CountyHamilton CountyHancock CountyHardin CountyHarrison CountyHenry CountyHoward CountyHumboldt CountyIda CountyIowa CountyJackson CountyJasper CountyJefferson CountyJohnson CountyJones CountyKeokuk CountyKossuth CountyLee CountyLinn CountyLouisa CountyLucas CountyLyon CountyMadison CountyMahaska CountyMarion CountyMarshall CountyMills CountyMitchell CountyMonona CountyMonroe CountyMontgomery CountyMuscatine CountyO'Brien CountyOsceola CountyPage CountyPalo Alto CountyPlymouth CountyPocahontas CountyPolk CountyPottawattamie CountyPoweshiek CountyRinggold CountySac CountyScott CountyShelby CountyStory CountyTama CountyTaylor CountyUnion CountyVan Buren CountyWapello CountyWarren CountyWashington CountyWayne CountyWebster CountyWinnebago CountyWinneshiek CountyWoodbury CountyWorth CountyWright CountySioux County Sioux
Counties of Iowa · Sioux highlighted

History

Formed in 1851 from Polk County

An old deed may name a county that no longer exists, or a boundary that has since moved.

Sioux County was created from Non-County Area 9 attached to Polk County on January 15, 1851, but was not fully organized at first. In 1853, it was attached to Woodbury County for revenue, election, and judicial purposes, and remained so through several organizational changes over the following two decades. Sioux County was fully organized and permanently detached from Woodbury County on February 10, 1870.

Boundary changes from the Newberry Library, Atlas of Historical County Boundaries.

  1. 1851
    Sioux County created Sioux created from Non-County Area 9 attached to Polk; Sioux not fully organized, not attached.
    from Polk
    · Iowa Acts 1850-1851, ch. 9, sec. 41/p. 36
  2. 1853
    Changed Sioux attached to Woodbury "for revenue, election, and judicial purposes".
    Woodbury
    · Iowa Acts 1852-1853, ch. 8, sec. 14/p. 24
  3. 1860
    Changed Sioux fully organized, detached from Woodbury.
    Woodbury
    · Swisher, "Organization of Counties," 576
  4. 1864
    Changed Sioux reattached to Woodbury "for judicial purposes."
    Woodbury
    · Iowa Acts 1864, ch. 47, secs. 2, 9/pp. 47-49
  5. 1870
    Changed Sioux fully organized, detached from Woodbury when judicial attachments of 30 March 1864 were repealed.
    Woodbury
    · Iowa Acts 1870, ch. 2, secs. 3-4/pp. 3-4

Land and parcels

What the maps cover in Sioux

Who publishes each layer, how good it is, and when we last checked.

Official
from the office that keeps the record
Good enough
a reliable statewide or national copy
Fallback
a guide only; check the official record
Missing
nothing public found yet

People and land

Sioux by the Census

Population
35,872 2020 Census count
Housing units
13,000 2020 Census count
Land area
768 square miles
Water area
1.1 square miles
People per sq mi
47 population ÷ land area

Source: US Census Bureau, 2020 Census; US Census Bureau, 2020 Gazetteer Files. Not endorsed or certified by the Census Bureau.

Rules and offices

Who to ask before you build, dig or sell

Official county pages only. We link to them; we do not copy them, because they change.

Inside a city or town, permits usually come from that city rather than the county.

Permits

Zoning and code

County government

See your own lot on these maps

Open Sioux County on Parcel Chart's free map and click your parcel. Save it with a free account; the full record of your place (site map, projects, documents) is Pro, in early access.

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Questions

Common questions about Sioux County

When was Sioux County founded?
Sioux County was founded in 1851, formed from Polk County, and named after Sioux.
What is the county seat of Sioux County?
The county seat of Sioux County is Orange City.
Is there an online parcel map for Sioux County?
Yes. Iowa Department of Homeland Security and Emergency Management (statewide parcels, mirrored by the University of Iowa) publishes a parcel map of 30,725 parcels, rated fallback here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Sioux County's boundary or name changed?
Sioux County was created in 1851 from Polk County. Since then the Atlas of Historical County Boundaries records 4 later changes, chiefly involving Woodbury County.
Who issues building permits in Sioux County?
The county's page on building permits: Apply for a gun permit. Inside a city or town, ask that city first.
Is my lot in a flood zone?
We do not have flood maps for Sioux County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

Nearby

Counties next door