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County · code 39123

Ottawa CountyOhio

Ottawa County is in northwest Ohio and was formed in 1840, with its county seat in Port Clinton.

  • Founded1840
  • County seatPort Clinton
  • Named forOdawa
  • Land area255 sq mi + 330 sq mi water
  • Population40,364 2020 Census
  • Parcels mapped36,105 checked 15 October 2026
Open the free map Click any parcel in Ottawa County: acreage, parcel id, address and who publishes the map. No sign-in.

Updated

SanduskyLucasErieWood Port Clinton Census outline · seat marked

Where it is

Ottawa on the map of Ohio

Ohio has 88 counties and county equivalents, each with its own records office. Shapes with a page are links.

Adams CountyAllen CountyAshland CountyAshtabula CountyAthens CountyAuglaize CountyBelmont CountyBrown CountyButler CountyCarroll CountyChampaign CountyClark CountyClermont CountyClinton CountyColumbiana CountyCoshocton CountyCrawford CountyCuyahoga CountyDarke CountyDefiance CountyDelaware CountyErie CountyFairfield CountyFayette CountyFranklin CountyFulton CountyGallia CountyGeauga CountyGreene CountyGuernsey CountyHamilton CountyHancock CountyHardin CountyHarrison CountyHenry CountyHighland CountyHocking CountyHolmes CountyHuron CountyJackson CountyJefferson CountyKnox CountyLake CountyLawrence CountyLicking CountyLogan CountyLorain CountyLucas CountyMadison CountyMahoning CountyMarion CountyMedina CountyMeigs CountyMercer CountyMiami CountyMonroe CountyMontgomery CountyMorgan CountyMorrow CountyMuskingum CountyNoble CountyPaulding CountyPerry CountyPickaway CountyPike CountyPortage CountyPreble CountyPutnam CountyRichland CountyRoss CountySandusky CountyScioto CountySeneca CountyShelby CountyStark CountySummit CountyTrumbull CountyTuscarawas CountyUnion CountyVan Wert CountyVinton CountyWarren CountyWashington CountyWayne CountyWilliams CountyWood CountyWyandot CountyOttawa County Ottawa
Counties of Ohio · Ottawa highlighted

History

Formed in 1840 from Erie County, Lucas County and Sandusky County

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

Ottawa County was created on March 6, 1840, from parts of Erie, Lucas, and Sandusky counties. The county lost territory to Sandusky in March 1840, to Erie in 1845, and to Lucas in 1850. The county is named after the Odawa people.

Boundary changes from the Newberry Library, Atlas of Historical County Boundaries.

  1. 1840
    Ottawa County created Ottawa created from Erie, Lucas, and Sandusky.
    from Eriefrom Lucasfrom Sandusky
    · Ohio Laws 1839, 38th assy., loc., p. 99
  2. 1840
    Lost territory Ottawa lost to Sandusky.
    to Sandusky
    · Ohio Laws 1839, 38th assy., loc., p. 201
  3. 1845
    Lost territory Ottawa lost Kelley's Island to Erie.
    to Erie
    · Ohio Laws 1844, 43d assy., loc., p. 300
  4. 1850
    Lost territory Ottawa lost to Lucas.
    to Lucas
    · Ohio Laws 1849, 48th assy., loc., p. 682

Land and parcels

What the maps cover in Ottawa

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

Ottawa by the Census

Population
40,364 2020 Census count
Housing units
28,596 2020 Census count
Land area
255 square miles
Water area
330 square miles · 56% of the county, including large bodies of water
People per sq mi
158 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

Permits

Zoning and code

County government

See your own lot on these maps

Open Ottawa 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 Ottawa County

When was Ottawa County founded?
Ottawa County was founded in 1840, formed from Erie County, Lucas County and Sandusky County, and named after Odawa.
What is the county seat of Ottawa County?
The county seat of Ottawa County is Port Clinton.
Is there an online parcel map for Ottawa County?
Yes. Ottawa County publishes a parcel map of 36,105 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Ottawa County's boundary or name changed?
Ottawa County was created in 1840 from Erie County, Lucas County and Sandusky County. Since then the Atlas of Historical County Boundaries records 3 later changes, chiefly involving Erie County, Lucas County and Sandusky County.
Who issues building permits in Ottawa 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 Ottawa County?
The county's page on septic systems and wells: Riverview HealthCare Campus.
Is my lot in a flood zone?
We do not have flood maps for Ottawa 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