When was Ross County founded?

Ross County was founded in 1798, formed from Adams County, Hamilton County and Washington County, and named after James Ross.

What is the county seat of Ross County?

The county seat of Ross County is Chillicothe.

Is there an online parcel map for Ross County?

Yes. A public source publishes a parcel map of 44,852 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.

Has Ross County's boundary or name changed?

Ross County was created in 1798 from Adams County, Hamilton County and Washington County. Since then the Atlas of Historical County Boundaries records 13 later changes, chiefly involving Jackson County, Hocking County and Pickaway County.

Is my lot in a flood zone?

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

County · code 39141

Ross CountyOhio

Ross County is a county in Ohio, with its seat in Chillicothe. It was created in 1798 by the Northwest Territory from parts of Adams, Hamilton, and Washington counties and named after James Ross.

Founded1798
County seatChillicothe
Named forJames Ross
Land area689 sq mi + 3.9 sq mi water
Population77,093 2020 Census
Parcels mapped44,852 checked 16 October 2026

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

Updated 20 October 2026

Census outline · seat marked

History

Formed in 1798 from Adams County, Hamilton County and Washington County

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

Ross County was created on August 20, 1798, from Adams, Hamilton, and Washington counties. The county became part of the state of Ohio in 1803 and subsequently lost territory to the creation of Fairfield (1800), Franklin (1803), Greene (1803), Highland (1805), Fayette and Pickaway (1810), Pike (1815), Jackson (1816), and Hocking (1818). In 1834 and 1839, Ross County gained small areas back from Hocking and Jackson counties.

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

1798
Ross County created Ross created by the Northwest Territory from Adams, Hamilton, and Washington.
from Adams from Hamilton from Washington
20 August 1798 · Terr. Papers U.S., 3:510; Chase, 3:ch. 336/p. 2097
1800
Lost territory Ross lost to creation of Fairfield.
to Fairfield
9 December 1800 · Terr. Papers U.S., 3:526; Chase, 3:ch. 340/pp. 2097-2098
1803
Became part of Ohio Ross 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
1803
Lost territory Ross lost to creation of Franklin.
to Franklin
30 April 1803 · Ohio Laws 1803, 1st assy., ch. 11/p. 26; Chase, 3:ch. 348/p. 2101
1803
Lost territory Ross lost to creation of Greene.
to Greene
1 May 1803 · Ohio Laws 1803, 1st assy., ch. 4, secs. 1-4, 8/pp. 9-12; Chase, 3:ch. 345/pp. 2099-2100

Show all 14 changes (9 more)

1798
Ross County created Ross created by the Northwest Territory from Adams, Hamilton, and Washington.
from Adams from Hamilton from Washington
20 August 1798 · Terr. Papers U.S., 3:510; Chase, 3:ch. 336/p. 2097
1800
Lost territory Ross lost to creation of Fairfield.
to Fairfield
9 December 1800 · Terr. Papers U.S., 3:526; Chase, 3:ch. 340/pp. 2097-2098
1803
Became part of Ohio Ross 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
1803
Lost territory Ross lost to creation of Franklin.
to Franklin
30 April 1803 · Ohio Laws 1803, 1st assy., ch. 11/p. 26; Chase, 3:ch. 348/p. 2101
1803
Lost territory Ross lost to creation of Greene.
to Greene
1 May 1803 · Ohio Laws 1803, 1st assy., ch. 4, secs. 1-4, 8/pp. 9-12; Chase, 3:ch. 345/pp. 2099-2100
1805
Lost territory Ross lost to creation of Highland.
to Highland
1 May 1805 · Ohio Laws 1804, 3d assy., ch. 60, sec. 1/p. 256; Chase, 3: ch. 350/p. 2102
1810
Lost territory Ross lost to creation of Fayette and Pickaway.
to Fayette to Pickaway
1 March 1810 · Ohio Laws 1809, 8th assy., ch. 13/p. 41 and ch. 39, secs. 1-2/pp. 138-139; Chase, 3:ch. 379/p. 2111 and ch. 382/p. 2113
1815
Lost territory Ross lost to creation of Pike.
to Pike
1 February 1815 · Ohio Laws 1814, 13th assy., ch. 16, secs. 1, 6/pp. 52, 55; Chase 3:ch. 399/pp. 2118-2119
1816
Lost territory Ross lost to creation of Jackson.
to Jackson
1 March 1816 · Ohio Laws 1815, 14th assy., ch. 25, secs. 1, 5/pp. 112, 115; Chase, 3:ch. 404/pp. 2121-2122
1818
Lost territory Ross lost to creation of Hocking and lost to Jackson.
to Hocking to Jackson
1 March 1818 · Ohio Laws 1817, 16th assy., ch. 24, secs. 1, 6/pp. 60, 62; Chase, 3:ch. 416/pp. 2127-2128
1834
Gained territory Ross gained from Hocking.
from Hocking
1 March 1834 · Ohio Laws 1833, 32d assy., loc., p. 240
1839
Gained territory Ross gained small area from Jackson.
from Jackson
11 January 1839 · Ohio Laws 1838, 37th assy., loc., p. 18
1843
Gained territory Ross gained small area from Pickaway in the town of Adelphi.
from Pickaway
7 March 1843 · Ohio Laws 1842, 41st assy., loc., p. 129
1850
Lost territory Ross lost to creation of Vinton.
to Vinton
1 April 1850 · Ohio Laws 1849, 48th assy., loc., secs. 1-3, 6/pp. 684-685

Land and parcels

What the maps cover in Ross

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

Parcels Good enough

Lot lines and tax-map numbers for 44,852 parcels. Drawn for tax purposes: usually within a few feet of a survey, but not a survey.
edited 24 February 2024 · checked 16 October 2026
Address points Official

One point per address, 36,236 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

Ross by the Census

Population

77,093 2020 Census count

Housing units

32,066 2020 Census count

Land area

689 square miles

Water area

3.9 square miles

People per sq mi

112 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

Ross County's official site

We have found the county's site but not its offices yet; start there.

County government

County government
The official website of Ross County.
pickawayross.com

See your own lot on these maps

Open Ross 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 Ross County

When was Ross County founded?: Ross County was founded in 1798, formed from Adams County, Hamilton County and Washington County, and named after James Ross.
What is the county seat of Ross County?: The county seat of Ross County is Chillicothe.
Is there an online parcel map for Ross County?: Yes. A public source publishes a parcel map of 44,852 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Ross County's boundary or name changed?: Ross County was created in 1798 from Adams County, Hamilton County and Washington County. Since then the Atlas of Historical County Boundaries records 13 later changes, chiefly involving Jackson County, Hocking County and Pickaway County.
Is my lot in a flood zone?: We do not have flood maps for Ross County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

Nearby