When was Island County founded?

Island County was founded in 1852, formed from Thurston County, and named after Whidbey Island, Washington.

What is the county seat of Island County?

The county seat of Island County is Coupeville.

Is there an online parcel map for Island County?

Yes. Island County publishes a parcel map of 54,018 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.

Has Island County's boundary or name changed?

Island County was created in 1852 from Thurston County. Since then the Atlas of Historical County Boundaries records 7 later changes, chiefly involving Whatcom County, Jefferson County and Snohomish County.

Who issues building permits in Island 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 Island County?

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

Is my lot in a flood zone?

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

County · code 53029

Island CountyWashington

Island County is a county in Washington, with its seat in Coupeville, formed in 1852.

Founded1852
County seatCoupeville
Named forWhidbey Island, Washington
Land area208 sq mi + 309 sq mi water
Population86,857 2020 Census
Parcels mapped54,018 checked 16 October 2026

Open the free map Click any parcel in Island 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.

Island County was created by Oregon Territory on December 22, 1852, from Thurston County and included the disputed San Juan Islands, which were claimed by both the United States and Great Britain until 1872. On March 2, 1853, Island became a county in Washington Territory when Oregon Territory's jurisdiction ended. The county was named after Whidbey Island.

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

1852
Island County created Island created by Oregon Territory from Thurston. Island included the disputed San Juan Islands which were claimed by both the United States and Great Britain.
from Thurston
22 December 1852 · Ore. Terr. Special Laws 1852, 4th reg. sess., pp. 46-47
1853
Became part of Washington Island became a county in Washington Territory; eliminated from Oregon Territory; included the disputed area of the San Juan Islands. 2 March 1853 · Wash. Terr. Laws, 1854, 1st. sess., p. 32; Van Zandt, 155
1854
Lost territory Island lost to the creation of Whatcom.
to Whatcom
9 March 1854 · Wash. Terr. Laws 1854, 1st sess., p. 475
1858
Lost territory Island lost to Whatcom.
to Whatcom
14 January 1858 · Wash. Terr. Laws 1857, 5th sess., p. 53
1889
Became part of Washington Island 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 12 changes (7 more, mostly small adjustments)

1852
Island County created Island created by Oregon Territory from Thurston. Island included the disputed San Juan Islands which were claimed by both the United States and Great Britain.
from Thurston
22 December 1852 · Ore. Terr. Special Laws 1852, 4th reg. sess., pp. 46-47
1853
Changed Jefferson attached to Island for judicial purposes. Attachment reconfirmed 1 February 1853.
Jefferson
24 January 1853 · Ore. Terr. Special Laws, 1852, 4th reg. sess., pp. 37, 52
1853
Became part of Washington Island became a county in Washington Territory; eliminated from Oregon Territory; included the disputed area of the San Juan Islands. 2 March 1853 · Wash. Terr. Laws, 1854, 1st. sess., p. 32; Van Zandt, 155
1854
Lost territory Island lost to the creation of Whatcom.
to Whatcom
9 March 1854 · Wash. Terr. Laws 1854, 1st sess., p. 475
1858
Lost territory Island lost to Whatcom.
to Whatcom
14 January 1858 · Wash. Terr. Laws 1857, 5th sess., p. 53
1861
Lost territory Island lost to creation of Snohomish.
to Snohomish
14 January 1861 · Wash. Terr. Laws 1860, 8th sess., p. 19
1867
Lost territory Island lost to Whatcom.
to Whatcom
31 January 1867 · Wash. Terr. Laws 1866-1867, 14th sess., p. 46
1868
Boundary clarified Island redefined to extend boundaries over water to "meet the boundary lines of the surrounding counties on all sides" (no change).
no change
21 January 1868 · Wash. Terr. Laws 1867, 1st biennial sess., p. 68
1869
Boundary clarified Island redefined (no change).
no change
2 December 1869 · Wash. Terr. Laws 1869, 2nd biennial sess., sec. 1/pp. 292-293
1877
Boundary clarified Island boundaries with San Juan and Whatcom redefined (no change).
with San Juan with Whatcomno change
9 November 1877 · Wash. Terr. Laws 1877, 6th biennial sess., pp. 425-426
1889
Became part of Washington Island 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
1891
Boundary clarified Island redefined to "include all of the islands known as Whidby, Canamo, Smith's, Deception, and Ure's" (no change).
no change
7 March 1891 · Wash. Laws 1891, 2nd leg. sess., p. 217

Land and parcels

What the maps cover in Island

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

Parcels Good enough

Lot lines and tax-map numbers for 54,018 parcels from Island County. 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 Island 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

Island by the Census

Population

86,857 2020 Census count

Housing units

41,922 2020 Census count

Land area

208 square miles

Water area

309 square miles · 60% of the county, including large bodies of water

People per sq mi

417 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

Assessor and property recordsfrom islandcountywa.gov · checked 13 October 2026
Clerk of court: deeds and platsfrom islandcountywa.gov · checked 13 October 2026

Permits

Health department: septic and wellfrom islandcountywa.gov · checked 13 October 2026
Permitsfrom islandcountywa.gov
Food Permitsfrom islandcountywa.gov
Plumbing and Mechanical Permit Fee Schedule (PDF)from islandcountywa.gov
Septic Records - OnlineRMEfrom islandcountywa.gov
Onsite Sewage (Septic) Systemsfrom islandcountywa.gov

Zoning and code

Planning and zoning 360-757-5964from islandcountywa.gov · checked 13 October 2026
Island County Flood Damage Prevention Ordinancefrom library.municode.com

GIS and maps

County GIS and mapsfrom islandcountywa.gov · checked 13 October 2026

County government

County government
The official website of Island County.
islandcountywa.gov

See your own lot on these maps

Open Island 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 Island County

When was Island County founded?: Island County was founded in 1852, formed from Thurston County, and named after Whidbey Island, Washington.
What is the county seat of Island County?: The county seat of Island County is Coupeville.
Is there an online parcel map for Island County?: Yes. Island County publishes a parcel map of 54,018 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Island County's boundary or name changed?: Island County was created in 1852 from Thurston County. Since then the Atlas of Historical County Boundaries records 7 later changes, chiefly involving Whatcom County, Jefferson County and Snohomish County.
Who issues building permits in Island 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 Island County?: The county's page on septic systems and wells: Behavioral Health.
Is my lot in a flood zone?: We do not have flood maps for Island 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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