When was Jefferson County founded?

Jefferson County was founded in 1852, formed from Thurston County, and named after Thomas Jefferson.

What is the county seat of Jefferson County?

The county seat of Jefferson County is Port Townsend.

Is there an online parcel map for Jefferson County?

Yes. A public source publishes a parcel map of 32,851 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.

Has Jefferson County's boundary or name changed?

Jefferson County was created in 1852 from Thurston County. Since then the Atlas of Historical County Boundaries records 13 later changes, chiefly involving Chehalis County, Clallam County and Grays Harbor County.

Who issues building permits in Jefferson County?

The county's page on building permits: Permits. Inside a city or town, ask that city first.

Who issues septic and well permits in Jefferson County?

The county's page on septic systems and wells: Board of Health.

Is my lot in a flood zone?

We do not have flood maps for Jefferson County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

County · code 53031

Jefferson CountyWashington

Jefferson County is a county in Washington state with its seat in Port Townsend, formed in 1852.

Founded1852
County seatPort Townsend
Named forThomas Jefferson
Land area1,804 sq mi + 384 sq mi water
Population32,977 2020 Census
Parcels mapped32,851 checked 16 October 2026

Open the free map Click any parcel in Jefferson County: acreage, parcel id, address and who publishes the map. No sign-in.

Updated 20 October 2026

Census outline · seat marked

History

Formed in 1852 from Thurston County

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

Jefferson County was created from Thurston County in the Oregon Territory on December 22, 1852, and named after Thomas Jefferson. When Oregon Territory became Washington Territory in 1853, Jefferson County transferred to Washington Territory. The county underwent several boundary adjustments over the following decades, losing land to the creation of Clallam County in 1854 and to Mason and Grays Harbor counties in 1867.

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

1852
Jefferson County created Jefferson created by Oregon Territory from Thurston.
from Thurston
22 December 1852 · Ore. Terr. Special Laws 1852, 4th reg. sess., p. 43
1853
Became part of Washington Jefferson became a county in Washington Territory; eliminated from Oregon Territory. 2 March 1853 · Wash. Terr. Laws, 1854, 1st. sess., p. 32; Van Zandt, 155
1854
Exchanged territory Jefferson exchanged with King.
with King
13 March 1854 · Wash. Terr. Laws 1854, 1st sess., p. 470
1854
Lost territory Jefferson lost to creation of Clallam.
to Clallam
26 April 1854 · Wash. Terr. Laws 1854, 1st sess., p. 472
1889
Became part of Washington Jefferson continued as a Washington county when the state of Washington admitted to the Union and Washington Territory eliminated. 11 November 1889 · U.S. Stat., vol. 25, ch. 180[1889], p. 676; U.S. Stat. pres. proc., vol. 26[1889], p. 10; Van Zandt, 155-156

Show all 14 changes (9 more)

1852
Jefferson County created Jefferson created by Oregon Territory from Thurston.
from Thurston
22 December 1852 · Ore. Terr. Special Laws 1852, 4th reg. sess., p. 43
1853
Changed Jefferson attached to Island for judicial purposes. Attachment reconfirmed 1 February 1853.
Island
24 January 1853 · Ore. Terr. Special Laws, 1852, 4th reg. sess., pp. 37, 52
1853
Changed Jefferson (Washington) attachment to Island (Washington) reconfirmed.
Island (Wash.)
1 February 1853 · Ore. Terr. Laws 1852, 4th reg. sess., p. 52
1853
Became part of Washington Jefferson became a county in Washington Territory; eliminated from Oregon Territory. 2 March 1853 · Wash. Terr. Laws, 1854, 1st. sess., p. 32; Van Zandt, 155
1854
Exchanged territory Jefferson exchanged with King.
with King
13 March 1854 · Wash. Terr. Laws 1854, 1st sess., p. 470
1854
Lost territory Jefferson lost to creation of Clallam.
to Clallam
26 April 1854 · Wash. Terr. Laws 1854, 1st sess., p. 472
1858
Exchanged territory Jefferson exchanged with Clallam.
with Clallam
1 February 1858 · Wash. Terr. Laws 1857, 5th sess., p. 52
1867
Lost territory Jefferson lost to Chehalis (now Grays Harbor) and Mason.
to Chehalis to Grays Harborto Mason
31 January 1867 · Wash. Terr. Laws 1866-1867, 14th sess., p. 45
1868
Lost territory Jefferson lost to creation of Quillehuyte (extinct).
to Quillehuyte
29 January 1868 · Wash. Terr. Laws 1867, 1st biennial sess., pp. 80-81
1869
Gained territory Jefferson gained from Quillehuyte (extinct) when the law creating Quillehuyte was repealed.
from Quillehuyte
2 December 1869 · Wash. Terr. Laws 1869, 2nd biennial sess., sec. 1/p. 292
1877
Lost territory Jefferson lost to Mason.
to Mason
9 November 1877 · Wash. Terr. Laws 1877, 6th biennial sess., pp. 406-407
1889
Became part of Washington Jefferson continued as a Washington county when the state of Washington admitted to the Union and Washington Territory eliminated. 11 November 1889 · U.S. Stat., vol. 25, ch. 180[1889], p. 676; U.S. Stat. pres. proc., vol. 26[1889], p. 10; Van Zandt, 155-156
1905
Gained territory Jefferson gained from Chehalis (now Grays Harbor) when the Washington Superior Court of Thurston County ruled that the boundary between the two counties was to run along the township line between T. 23 N. and T. 24 N.
from Chehalis from Grays Harborfrom Thurston
19 September 1905 · Wash. State Archives, "Jefferson County v Chehalis County" Superior Court records of the state of Wash. in and for Thurston County [1905]
1925
Changed West boundary of Jefferson extended into the Pacific Ocean to intersect the west boundary of the State of Washington. 14 December 1925 · Wash. Laws 1925, 19th leg. extra sess., ch. 40/p. 29

Land and parcels

What the maps cover in Jefferson

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

Parcels Good enough

Lot lines and tax-map numbers for 32,851 parcels. Drawn for tax purposes: usually within a few feet of a survey, but not a survey.
checked 16 October 2026
Address points Missing

No public address points layer found for Jefferson County yet.
Buildings Reference

Roof outlines traced from aerial imagery from FEMA Response Geospatial Office with Oak Ridge National Laboratory (ORNL). Good for seeing what is on a lot; not accurate enough to set a fence from.
checked 18 October 2026

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

Jefferson by the Census

Population

32,977 2020 Census count

Housing units

19,087 2020 Census count

Land area

1,804 square miles

Water area

384 square miles

People per sq mi

18 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.

Records

Clerk of court: deeds and plats
Clerk's Office
from co.jefferson.wa.us · checked 13 October 2026

Permits

Health department: septic and wellfrom co.jefferson.wa.us · checked 13 October 2026
Permitsfrom co.jefferson.wa.us
Building Permitsfrom co.jefferson.wa.us
Septic Systemsfrom co.jefferson.wa.us
Septic System FAQsfrom co.jefferson.wa.us

Zoning and code

Planning and zoningfrom co.jefferson.wa.us · checked 13 October 2026
Burn Regulation Ordinancefrom co.jefferson.wa.us
2025 Critical Area Ordinance Updatefrom co.jefferson.wa.us
UGA Zoningfrom test.co.jefferson.wa.us

County government

County government
The official website of Jefferson County.
co.jefferson.wa.us

See your own lot on these maps

Open Jefferson 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.

Open the free map no sign-in Pro early access

Questions

Common questions about Jefferson County

When was Jefferson County founded?: Jefferson County was founded in 1852, formed from Thurston County, and named after Thomas Jefferson.
What is the county seat of Jefferson County?: The county seat of Jefferson County is Port Townsend.
Is there an online parcel map for Jefferson County?: Yes. A public source publishes a parcel map of 32,851 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Jefferson County's boundary or name changed?: Jefferson County was created in 1852 from Thurston County. Since then the Atlas of Historical County Boundaries records 13 later changes, chiefly involving Chehalis County, Clallam County and Grays Harbor County.
Who issues building permits in Jefferson County?: The county's page on building permits: Permits. Inside a city or town, ask that city first.
Who issues septic and well permits in Jefferson County?: The county's page on septic systems and wells: Board of Health.
Is my lot in a flood zone?: We do not have flood maps for Jefferson County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

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