When was Fairfield County founded?

Fairfield County was founded in 1800, formed from Ross County and Washington County.

What is the county seat of Fairfield County?

The county seat of Fairfield County is Lancaster.

Is there an online parcel map for Fairfield County?

Yes. Fairfield County publishes a parcel map of 75,113 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.

Has Fairfield County's boundary or name changed?

Fairfield County was created in 1800 from Ross County and Washington County. Since then the Atlas of Historical County Boundaries records 7 later changes, chiefly involving Franklin County, Hocking County and Knox County.

Who issues building permits in Fairfield County?

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

Is my lot in a flood zone?

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

County · code 39045

Fairfield CountyOhio

Fairfield County is a county in Ohio with its seat in Lancaster, formed in 1800.

Founded1800
County seatLancaster
Land area504 sq mi + 4.2 sq mi water
Population158,921 2020 Census
Parcels mapped75,113 checked 15 October 2026

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

Updated 20 October 2026

Census outline · seat marked

History

Formed in 1800 from Ross County and Washington County

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

Fairfield was created by the Northwest Territory from Ross and Washington counties on December 9, 1800, and became a county in the state of Ohio on March 1, 1803. The county was significantly reduced over the following decades through losses to the creation of other counties: Muskingum in 1804, Knox and Licking in 1808, Franklin in 1808, Pickaway in 1810, Hocking and Perry in 1818, Hocking again in 1850, and Franklin again in 1851.

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

1800
Fairfield County created Fairfield created by the Northwest Territory from Ross and Washington.
from Ross from Washington
9 December 1800 · Terr. Papers U.S., 3:526; Chase, 3:ch. 340/pp. 2097-2098
1803
Became part of Ohio Fairfield became a county in the state of Ohio. 1 March 1803 · U.S. Stat., vol. 2, ch. 40 [1802], secs. 1-3/pp. 173-174; Van Zandt, 112
1804
Lost territory Fairfield lost to creation of Muskingum.
to Muskingum
1 March 1804 · Ohio Laws 1803, 2d assy., ch. 6, secs. 1-4/pp. 68-70; Chase, 3:ch. 349/p. 2101
1808
Lost territory Fairfield lost to creation of Knox and Licking, and lost to Franklin.
to Knox to Licking to Franklin
1 March 1808 · Ohio Laws 1807, 6th assy., ch. 8, secs. 1-2, 7/pp. 21-24; Chase, 3:ch. 364, secs. 1-2, 7/pp. 2106-2107
1810
Lost territory Fairfield lost to creation of Pickaway.
to Pickaway
1 March 1810 · Ohio Laws 1809, 8th assy., ch. 13/p. 41; Chase, 3:ch. 379/p. 2111

Show all 8 changes (3 more)

1800
Fairfield County created Fairfield created by the Northwest Territory from Ross and Washington.
from Ross from Washington
9 December 1800 · Terr. Papers U.S., 3:526; Chase, 3:ch. 340/pp. 2097-2098
1803
Became part of Ohio Fairfield became a county in the state of Ohio. 1 March 1803 · U.S. Stat., vol. 2, ch. 40 [1802], secs. 1-3/pp. 173-174; Van Zandt, 112
1804
Lost territory Fairfield lost to creation of Muskingum.
to Muskingum
1 March 1804 · Ohio Laws 1803, 2d assy., ch. 6, secs. 1-4/pp. 68-70; Chase, 3:ch. 349/p. 2101
1808
Lost territory Fairfield lost to creation of Knox and Licking, and lost to Franklin.
to Knox to Licking to Franklin
1 March 1808 · Ohio Laws 1807, 6th assy., ch. 8, secs. 1-2, 7/pp. 21-24; Chase, 3:ch. 364, secs. 1-2, 7/pp. 2106-2107
1810
Lost territory Fairfield lost to creation of Pickaway.
to Pickaway
1 March 1810 · Ohio Laws 1809, 8th assy., ch. 13/p. 41; Chase, 3:ch. 379/p. 2111
1818
Lost territory Fairfield lost to creation of Hocking and Perry.
to Hocking to Perry
1 March 1818 · Ohio Laws 1817, 16th assy., ch. 11, secs. 1, 5/pp. 26, 29 and ch. 24, secs. 1, 6/pp. 60, 62; Chase, 3:ch. 411/p. 2124 and ch. 416/pp. 2127-2128
1850
Lost territory Fairfield lost to Hocking.
to Hocking
1 April 1850 · Ohio Laws 1849, 48th assy., loc., secs. 1-3, 6/pp. 684-685
1851
Lost territory Fairfield lost to Franklin.
to Franklin
25 March 1851 · Ohio Laws 1850, 49th assy., loc., p. 150

Land and parcels

What the maps cover in Fairfield

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

Parcels Good enough

Lot lines and tax-map numbers for 75,113 parcels from Fairfield County. Drawn for tax purposes: usually within a few feet of a survey, but not a survey.
checked 15 October 2026
Address points Official

One point per address, 70,882 in all from Ohio Geographically Referenced Information Program (OGRIP), Ohio DAS/OIT (state GIS office).
edited 24 June 2025 · checked 13 October 2026
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

Fairfield by the Census

Population

158,921 2020 Census count

Housing units

62,466 2020 Census count

Land area

504 square miles

Water area

4.2 square miles

People per sq mi

315 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

Permits & Certificatesfrom co.fairfield.oh.us
Forms + Permitsfrom co.fairfield.oh.us

Zoning and code

Planning and zoning 740-756-9221from co.fairfield.oh.us · checked 13 October 2026
rezoning application deadlinesfrom co.fairfield.oh.us

County government

County government
The official website of Fairfield County.
co.fairfield.oh.us

See your own lot on these maps

Open Fairfield 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 Fairfield County

When was Fairfield County founded?: Fairfield County was founded in 1800, formed from Ross County and Washington County.
What is the county seat of Fairfield County?: The county seat of Fairfield County is Lancaster.
Is there an online parcel map for Fairfield County?: Yes. Fairfield County publishes a parcel map of 75,113 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Fairfield County's boundary or name changed?: Fairfield County was created in 1800 from Ross County and Washington County. Since then the Atlas of Historical County Boundaries records 7 later changes, chiefly involving Franklin County, Hocking County and Knox County.
Who issues building permits in Fairfield County?: The county's page on building permits: Permits & Certificates. Inside a city or town, ask that city first.
Is my lot in a flood zone?: We do not have flood maps for Fairfield County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

Nearby