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County · code 19103

Johnson CountyIowa

Johnson County is a county in Iowa with its seat in Iowa City, formed on December 21, 1837.

  • Founded1837
  • County seatIowa City
  • Named forRichard Mentor Johnson
  • Land area613 sq mi + 10 sq mi water
  • Population152,854 2020 Census
  • Parcels mapped74,442 checked 15 October 2026
Open the free map Click any parcel in Johnson County: acreage, parcel id, address and who publishes the map. No sign-in.

Updated

WashingtonLinnIowaLouisa Iowa City Census outline · seat marked

Where it is

Johnson 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 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 CountySioux CountyStory CountyTama CountyTaylor CountyUnion CountyVan Buren CountyWapello CountyWarren CountyWashington CountyWayne CountyWebster CountyWinnebago CountyWinneshiek CountyWoodbury CountyWorth CountyWright CountyJohnson County Johnson
Counties of Iowa · Johnson highlighted

History

Formed in 1837 from Cook County, Dubuque County, Muscatine County and Cedar County

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

Johnson County was formed in 1837 from Cook County, Dubuque County, Muscatine County and Cedar County, and named after Richard Mentor Johnson. Iowa City is the county seat.

Deeds and plats from before 1837 for land now in Johnson County may have been recorded in Cook County, Dubuque County, Muscatine County and Cedar County.

Boundary changes from the Newberry Library, Atlas of Historical County Boundaries; the 5 that matter most are shown first.

  1. 1837
    Johnson County created Johnson created by Wisconsin Territory from Cook (extinct), Dubuque, Muscatine, and Non-County Area 1; Johnson not fully organized, attached to Cedar "for temporary purposes."
    from Cookfrom Dubuquefrom Muscatinefrom Cedar
    · Wis. Terr. Laws 1837, no. 6, secs. 14, 16/pp. 135-136
  2. 1838
    Became part of Iowa Johnson became an Iowa Territory county when Iowa Territory was created from Wisconsin Territory. · U.S. Stat., vol. 5, ch. 96[1838]/pp. 235-241
  3. 1838
    Changed Johnson fully organized, detached from Cedar; Keokuk detached from Cedar, attached to Johnson "for judicial purposes."
    CedarKeokuk
    · History of Johnson, 172; Wis. Terr. Laws 1838, spec. sess., no. 10, sec. 1/pp. 543-544
  4. 1843
    Changed Keokuk detached from Johnson, attached to Washington "for judicial, revenue, and election purposes."
    KeokukWashington
    · Iowa Terr. Rev. Stat. 1843, ch. 34, sec. 5/p. 132
  5. 1846
    Became part of Iowa Johnson became an Iowa county when the state of Iowa was created from Iowa Territory. · U.S. Stat., vol. 9, ch. 1[1847]/p. 117
Show all 9 changes (4 more)
  1. 1837
    Johnson County created Johnson created by Wisconsin Territory from Cook (extinct), Dubuque, Muscatine, and Non-County Area 1; Johnson not fully organized, attached to Cedar "for temporary purposes."
    from Cookfrom Dubuquefrom Muscatinefrom Cedar
    · Wis. Terr. Laws 1837, no. 6, secs. 14, 16/pp. 135-136
  2. 1838
    Became part of Iowa Johnson became an Iowa Territory county when Iowa Territory was created from Wisconsin Territory. · U.S. Stat., vol. 5, ch. 96[1838]/pp. 235-241
  3. 1838
    Changed Johnson fully organized, detached from Cedar; Keokuk detached from Cedar, attached to Johnson "for judicial purposes."
    CedarKeokuk
    · History of Johnson, 172; Wis. Terr. Laws 1838, spec. sess., no. 10, sec. 1/pp. 543-544
  4. 1839
    Lost territory Johnson lost to Washington.
    to Washington
    · Iowa Terr. Laws 1838-1839, pp. 100-101
  5. 1843
    Changed Keokuk detached from Johnson, attached to Washington "for judicial, revenue, and election purposes."
    KeokukWashington
    · Iowa Terr. Rev. Stat. 1843, ch. 34, sec. 5/p. 132
  6. 1844
    Changed Iowa attached to Johnson "for judicial, revenue, and election purposes" (Poweshiek and Non-County Area 8 indirectly attached to Johnson, through Iowa, until 1 March 1844)
    IowaPoweshiek
    · Iowa Terr. Laws 1843-1844, ch. 4, secs. 1-2/p. 3
  7. 1845
    Gained territory Johnson gained from Washington.
    from Washington
    · Iowa Terr. Laws 1845, ch. 45, sec. 1/pp. 66-67
  8. 1845
    Changed Iowa fully organized, detached from Johnson.
    Iowa
    · Iowa Terr. Laws 1845, ch. 55, sec. 1/pp. 85-88
  9. 1846
    Became part of Iowa Johnson became an Iowa county when the state of Iowa was created from Iowa Territory. · U.S. Stat., vol. 9, ch. 1[1847]/p. 117

Land and parcels

What the maps cover in Johnson

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

Johnson by the Census

Population
152,854 2020 Census count
Housing units
65,916 2020 Census count
Land area
613 square miles
Water area
10 square miles
People per sq mi
249 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

County government

See your own lot on these maps

Open Johnson 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 Johnson County

When was Johnson County founded?
Johnson County was founded in 1837, formed from Cook County, Dubuque County, Muscatine County and Cedar County, and named after Richard Mentor Johnson.
What is the county seat of Johnson County?
The county seat of Johnson County is Iowa City.
Is there an online parcel map for Johnson County?
Yes. Johnson County publishes a parcel map of 74,442 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Johnson County's boundary or name changed?
Johnson County was created in 1837 from Cook County, Dubuque County, Muscatine County and Cedar County. Since then the Atlas of Historical County Boundaries records 8 later changes, chiefly involving Washington County, Iowa County and Keokuk County.
Who issues building permits in Johnson County?
The county's page on building permits: Get a permit. Inside a city or town, ask that city first.
Is my lot in a flood zone?
We do not have flood maps for Johnson 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