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County · code 42125

Washington CountyPennsylvania

Washington County is in Pennsylvania and has its county seat in Washington. It was formed on March 28, 1781, from Westmoreland County and named after George Washington.

  • Founded1781
  • County seatWashington
  • Named forGeorge Washington
  • Land area857 sq mi + 3.8 sq mi water
  • Population209,349 2020 Census
  • Parcels mapped125,730 checked 14 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

GreeneBrooke, WVAlleghenyHancock, WVFayetteWestmoreland Washington Census outline · seat marked

Where it is

Washington on the map of Pennsylvania

Pennsylvania has 67 counties and county equivalents, each with its own records office. Shapes with a page are links.

Adams CountyAllegheny CountyArmstrong CountyBeaver CountyBedford CountyBerks CountyBlair CountyBradford CountyBucks CountyButler CountyCambria CountyCameron CountyCarbon CountyCentre CountyChester CountyClarion CountyClearfield CountyClinton CountyColumbia CountyCrawford CountyCumberland CountyDauphin CountyDelaware CountyElk CountyErie CountyFayette CountyForest CountyFranklin CountyFulton CountyGreene CountyHuntingdon CountyIndiana CountyJefferson CountyJuniata CountyLackawanna CountyLancaster CountyLawrence CountyLebanon CountyLehigh CountyLuzerne CountyLycoming CountyMcKean CountyMercer CountyMifflin CountyMonroe CountyMontgomery CountyMontour CountyNorthampton CountyNorthumberland CountyPerry CountyPhiladelphia CountyPike CountyPotter CountySchuylkill CountySnyder CountySomerset CountySullivan CountySusquehanna CountyTioga CountyUnion CountyVenango CountyWarren CountyWayne CountyWestmoreland CountyWyoming CountyYork CountyWashington County Washington
Counties of Pennsylvania · Washington highlighted

History

Formed in 1781 from Westmoreland County

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

Washington County was created from Westmoreland County in 1781. Between 1788 and 1800, portions of the county were lost to the creation of Allegheny County, Greene County, and Beaver County. In 1802, Washington County gained territory from Greene County.

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

  1. 1781
    Washington County created Washington created from Westmoreland.
    from Westmoreland
    · Pa. Stat., ch. 931, sec. 1/10:272-273
  2. 1788
    Lost territory Washington lost to the creation of Allegheny.
    to Allegheny
    · Pa. Stat., ch. 1359, sec. 1/13:84-85
  3. 1789
    Lost territory Washington lost to Allegheny.
    to Allegheny
    · Pa. Stat., ch. 1435, sec. 1/13:319-320
  4. 1796
    Lost territory Washington lost to the creation of Greene.
    to Greene
    · Pa. Stat., ch. 1870, sec. 1/15:380-381
  5. 1800
    Lost territory Washington lost to the creation of Beaver.
    to Beaver
    · Pa. Stat., ch. 2130, pp. 454-455, 460-461
Show all 8 changes (3 more, mostly small adjustments)
  1. 1781
    Washington County created Washington created from Westmoreland.
    from Westmoreland
    · Pa. Stat., ch. 931, sec. 1/10:272-273
  2. 1788
    Lost territory Washington lost to the creation of Allegheny.
    to Allegheny
    · Pa. Stat., ch. 1359, sec. 1/13:84-85
  3. 1789
    Lost territory Washington lost to Allegheny.
    to Allegheny
    · Pa. Stat., ch. 1435, sec. 1/13:319-320
  4. 1796
    Lost territory Washington lost to the creation of Greene.
    to Greene
    · Pa. Stat., ch. 1870, sec. 1/15:380-381
  5. 1800
    Lost territory Washington lost to the creation of Beaver.
    to Beaver
    · Pa. Stat., ch. 2130, pp. 454-455, 460-461
  6. 1802
    Gained territory Washington gained from Greene.
    from Greene
    · Pa. Stat., ch. 2223, secs. 1-2/17:40-41
  7. 1807
    Changed Middle of Monongahela River fixed as boundary of adjoining counties, including Washington (no change). · Pa. Stat., ch. 2863, sec. 1/18:644
  8. 1887
    Boundary clarified Boundary between Washington and Greene clarified (no change).
    with Greeneno change
    · "Report of Commissioners, May 1900." Pa. State Arch., Land Office Recs., no. 66, item 3

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
209,349 2020 Census count
Housing units
96,791 2020 Census count
Land area
857 square miles
Water area
3.8 square miles
People per sq mi
244 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

Washington County's official site

We have found the county's site but not its offices yet; start there.

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 1781, formed from Westmoreland County, and named after George Washington.
What is the county seat of Washington County?
The county seat of Washington County is Washington.
Is there an online parcel map for Washington County?
Yes. A public source publishes a parcel map of 125,730 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 1781 from Westmoreland County. Since then the Atlas of Historical County Boundaries records 5 later changes, chiefly involving Allegheny County, Greene County and Beaver 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