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County · code 39165

Warren CountyOhio

Warren County is located in Ohio and was formed on May 1, 1803, from Hamilton County. The county seat is Lebanon.

  • Founded1803
  • County seatLebanon
  • Named forJoseph Warren
  • Land area401 sq mi + 6.1 sq mi water
  • Population242,337 2020 Census
  • Parcels mapped106,237 checked 14 October 2026
Open the free map Click any parcel in Warren County: acreage, parcel id, address and who publishes the map. No sign-in.

Updated

ClintonClermontButlerHamilton Lebanon Census outline · seat marked

Where it is

Warren 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 CountyOttawa CountyPaulding CountyPerry CountyPickaway CountyPike CountyPortage CountyPreble CountyPutnam CountyRichland CountyRoss CountySandusky CountyScioto CountySeneca CountyShelby CountyStark CountySummit CountyTrumbull CountyTuscarawas CountyUnion CountyVan Wert CountyVinton CountyWashington CountyWayne CountyWilliams CountyWood CountyWyandot CountyWarren County Warren
Counties of Ohio · Warren highlighted

History

Formed in 1803 from Hamilton County

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

Warren County was created from Hamilton County in 1803 and named after Joseph Warren. The county lost territory to the creation of Clinton County in 1810, then gained territory from Butler County and lost more to Clinton County in 1815.

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

  1. 1803
    Warren County created Warren created from Hamilton.
    from Hamilton
    · Ohio Laws 1803, 1st assy., ch. 4, secs. 1-4, 8/pp. 9-12; Chase, 3:ch. 345/pp. 2099-2100
  2. 1810
    Lost territory Warren lost to creation of Clinton.
    to Clinton
    · Ohio Laws 1809, 8th assy., ch. 63/p. 236; Chase, 3:ch. 384/pp. 2113-2114
  3. 1815
    Gained territory Warren gained from Butler, lost to Clinton.
    from Butlerfrom Clinton
    · Ohio Laws 1814, 13th assy., ch. 31, secs. 1, 2, 4, 5/pp. 109-112; Chase, 3:ch. 400/pp. 2119-2120
  4. 1859
    Changed Legislature authorized Clermont to gain small area from Warren dependent on local referendum.
    Clermont
    · Ohio Laws 1859, 53d assy., 2d sess., loc., p. 296

Land and parcels

What the maps cover in Warren

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

Warren by the Census

Population
242,337 2020 Census count
Housing units
93,276 2020 Census count
Land area
401 square miles
Water area
6.1 square miles
People per sq mi
604 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.

Permits

Zoning and code

County government

See your own lot on these maps

Open Warren 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 Warren County

When was Warren County founded?
Warren County was founded in 1803, formed from Hamilton County, and named after Joseph Warren.
What is the county seat of Warren County?
The county seat of Warren County is Lebanon.
Is there an online parcel map for Warren County?
Yes. Ohio Geographically Referenced Information Program (OGRIP, Ohio DAS) statewide compilation of county auditor parcels publishes a parcel map of 106,237 parcels, rated fallback here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Warren County's boundary or name changed?
Warren County was created in 1803 from Hamilton County. Since then the Atlas of Historical County Boundaries records 3 later changes, chiefly involving Clinton County, Butler County and Clermont County.
Who issues building permits in Warren County?
The county's page on building permits: Building Permit Fees. Inside a city or town, ask that city first.
Is my lot in a flood zone?
We do not have flood maps for Warren 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