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County · code 29221

Washington CountyMissouri

Washington County is a county in Missouri with its seat in Potosi. It was formed in 1813 and named after George Washington.

  • Founded1813
  • County seatPotosi
  • Named forGeorge Washington
  • Land area760 sq mi + 2.6 sq mi water
  • Population23,514 2020 Census
  • Parcels mapped26,757 checked 15 October 2026
Open the free map Click any parcel in Washington County: acreage, parcel id, address and who publishes the map. No sign-in.

Updated

IronCrawfordSt. FrancoisJeffersonFranklin Potosi Census outline · seat marked

Where it is

Washington on the map of Missouri

Missouri has 115 counties and county equivalents, each with its own records office. Shapes with a page are links.

Adair CountyAndrew CountyAtchison CountyAudrain CountyBarry CountyBarton CountyBates CountyBenton CountyBollinger CountyBoone CountyBuchanan CountyButler CountyCaldwell CountyCallaway CountyCamden CountyCape Girardeau CountyCarroll CountyCarter CountyCass CountyCedar CountyChariton CountyChristian CountyClark CountyClay CountyClinton CountyCole CountyCooper CountyCrawford CountyDade CountyDallas CountyDaviess CountyDeKalb CountyDent CountyDouglas CountyDunklin CountyFranklin CountyGasconade CountyGentry CountyGreene CountyGrundy CountyHarrison CountyHenry CountyHickory CountyHolt CountyHoward CountyHowell CountyIron CountyJackson CountyJasper CountyJefferson CountyJohnson CountyKnox CountyLaclede CountyLafayette CountyLawrence CountyLewis CountyLincoln CountyLinn CountyLivingston CountyMcDonald CountyMacon CountyMadison CountyMaries CountyMarion CountyMercer CountyMiller CountyMississippi CountyMoniteau CountyMonroe CountyMontgomery CountyMorgan CountyNew Madrid CountyNewton CountyNodaway CountyOregon CountyOsage CountyOzark CountyPemiscot CountyPerry CountyPettis CountyPhelps CountyPike CountyPlatte CountyPolk CountyPulaski CountyPutnam CountyRalls CountyRandolph CountyRay CountyReynolds CountyRipley CountySt. Charles CountySt. Clair CountySte. Genevieve CountySt. Francois CountySt. Louis CountySaline CountySchuyler CountyScotland CountyScott CountyShannon CountyShelby CountyStoddard CountyStone CountySullivan CountyTaney CountyTexas CountyVernon CountyWarren CountyWayne CountyWebster CountyWorth CountyWright CountySt. Louis cityWashington County Washington
Counties of Missouri · Washington highlighted

History

Formed in 1813 from St. Louis County and Ste. Genevieve County

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

Washington County was created in 1813 from St. Louis and Ste. Genevieve counties. Over the following decades, the county's boundaries changed through multiple transfers and the creation of new counties: it gained and lost territory to various neighboring counties including Cape Girardeau, St. Francois, Franklin, Jefferson, and Wayne. In 1821, St. Francois County was created from Washington County's territory, and later in 1857, Iron County was created from Washington County.

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

  1. 1813
    Washington County created Washington created from St. Louis and Ste. Genevieve.
    from St. Louisfrom Ste. Genevieve
    · Mo. Terr. Laws 1813-1814, ch. 95, secs. 1,11/pp. 285-290; Violette, 78
  2. 1813
    Gained territory Washington gained from Cape Girardeau and Ste. Genevieve, exchanged with St. Louis.
    from Cape Girardeaufrom Ste. Genevievefrom St. Louis
    · Mo. Terr. Laws 1813-1814, ch. 99, sec. 1/pp. 293-295
  3. 1821
    Lost territory Washington lost to creation of St. Francois.
    to St. Francois
    · Mo. Laws 1821-1822, ch. 26, sec. 1/pp. 28-30
  4. 1825
    Gained territory Washington gained from Franklin and Jefferson, lost to Wayne, Non-County Area 8, Non-County Area 11, and Non-County Area 13; inadvertently lost to creation of Non-County Area 14. Non-County Area 13 attached to Washington "for administrative and judicial purposes."
    from Franklinfrom Jeffersonfrom Wayne
    · Mo. Laws Rev., 1825, ch. 1. Secs. 6, 9/p. 233-234
  5. 1833
    Lost territory Washington lost attached Non-County Area 13 to Ripley; Non-County Area 13 eliminated.
    to Ripley
    · Mo. Laws 1832-1833, pub., secs. 1-2/pp. 55-56 and ch. 33, sec. 1/pp. 56-57
Show all 10 changes (5 more)
  1. 1813
    Washington County created Washington created from St. Louis and Ste. Genevieve.
    from St. Louisfrom Ste. Genevieve
    · Mo. Terr. Laws 1813-1814, ch. 95, secs. 1,11/pp. 285-290; Violette, 78
  2. 1813
    Gained territory Washington gained from Cape Girardeau and Ste. Genevieve, exchanged with St. Louis.
    from Cape Girardeaufrom Ste. Genevievefrom St. Louis
    · Mo. Terr. Laws 1813-1814, ch. 99, sec. 1/pp. 293-295
  3. 1821
    Lost territory Washington lost to creation of St. Francois.
    to St. Francois
    · Mo. Laws 1821-1822, ch. 26, sec. 1/pp. 28-30
  4. 1825
    Gained territory Washington gained from Franklin and Jefferson, lost to Wayne, Non-County Area 8, Non-County Area 11, and Non-County Area 13; inadvertently lost to creation of Non-County Area 14. Non-County Area 13 attached to Washington "for administrative and judicial purposes."
    from Franklinfrom Jeffersonfrom Wayne
    · Mo. Laws Rev., 1825, ch. 1. Secs. 6, 9/p. 233-234
  5. 1833
    Lost territory Washington lost attached Non-County Area 13 to Ripley; Non-County Area 13 eliminated.
    to Ripley
    · Mo. Laws 1832-1833, pub., secs. 1-2/pp. 55-56 and ch. 33, sec. 1/pp. 56-57
  6. 1833
    Lost territory Washington lost to St. Francois.
    to St. Francois
    · Mo. Laws 1832-1833, pub., ch. 34, sec. 1/p. 57
  7. 1837
    Changed Shannon attached to Ripley and Washington "for all civil and military purposes."
    ShannonRipley
    · Mo. Laws 1836-1837, pub., pp. 54-55
  8. 1841
    Changed Shannon fully organized, detached from Washington.
    Shannon
    · Mo. Laws 1840-1841, pub., secs. 43-45/p. 37
  9. 1857
    Lost territory Washington lost to creation of Iron, and lost to St. Francois.
    to Ironto St. Francois
    · Mo. Laws 1856-1857, gen., pp. 52-55
  10. 1857
    Lost territory Washington lost to Iron.
    to Iron
    · Mo. Laws 1856-1857, gen., p. 55

Land and parcels

What the maps cover in Washington

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

Washington by the Census

Population
23,514 2020 Census count
Housing units
10,719 2020 Census count
Land area
760 square miles
Water area
2.6 square miles
People per sq mi
31 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.

Records

County government

See your own lot on these maps

Open Washington 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 Washington County

When was Washington County founded?
Washington County was founded in 1813, formed from St. Louis County and Ste. Genevieve County, and named after George Washington.
What is the county seat of Washington County?
The county seat of Washington County is Potosi.
Is there an online parcel map for Washington County?
Yes. Washington County publishes a parcel map of 26,757 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Washington County's boundary or name changed?
Washington County was created in 1813 from St. Louis County and Ste. Genevieve County. Since then the Atlas of Historical County Boundaries records 9 later changes, chiefly involving St. Francois County, Iron County and Ripley County.
Is my lot in a flood zone?
We do not have flood maps for Washington 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