When was Knox County founded?

Knox County was founded in 1790, and named after Henry Knox.

What is the county seat of Knox County?

The county seat of Knox County is Vincennes.

Is there an online parcel map for Knox County?

Yes. Indiana Geographic Information Office (IndianaMap) publishes a parcel map of 29,961 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.

Has Knox County's boundary or name changed?

Knox County was created in 1790. Since then the Atlas of Historical County Boundaries records 16 later changes, chiefly involving Wayne County, Hamilton County and Sullivan County.

Who issues septic and well permits in Knox County?

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

Is my lot in a flood zone?

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

County · code 18083

Knox CountyIndiana

Knox County is in southwestern Indiana with its county seat in Vincennes. Knox County was created in 1790 and named after Henry Knox.

Founded1790
County seatVincennes
Named forHenry Knox
Land area516 sq mi + 8.1 sq mi water
Population36,282 2020 Census
Parcels mapped29,961 checked 15 October 2026

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

Updated 20 October 2026

Census outline · seat marked

History

Founded in 1790

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

Knox County was created by the Northwest Territory on June 20, 1790, from non-county area and originally included all of present Indiana and parts of present Illinois, Michigan, Ohio, and Wisconsin. Knox County lost territory in 1796 when Wayne County was created from the Northwest Territory, removing most of the county's lands in present-day Michigan and Wisconsin. Knox County became a county in Indiana Territory on July 4, 1800, when the United States created Indiana Territory from the Northwest Territory.

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

1790
Knox County created Knox created by Northwest Territory from non-county area; Knox included all of present Indiana, plus parts of present Illinois, Michigan, Ohio, and Wisconsin. 20 June 1790 · Terr. Papers U.S., 3:313
1796
Lost territory Knox lost to creation of Wayne (Northwest Territory, extinct).
to Wayne
15 August 1796 · Terr. Papers U.S., 2:567-568, and 3:447; Pence and Armstrong, 216
1798
Lost territory Knox lost to Hamilton (Ohio) in present Indiana and Ohio.
to Hamilton
22 June 1798 · Terr. Papers U.S., 3:509
1800
Became part of Indiana Knox became a county in Indiana Territory when the United States created Indiana Territory from the Northwest Territory. 4 July 1800 · Terr. Papers U.S., 3:86-88; U.S. Stat., vol. 2, ch. 41 [1800]/pp. 58-59
1801
Gained territory Knox gained from non-county area in Indiana Territory, including parts of present Indiana, Michigan, and Ohio; lost to Randolph (Illinois) and St. Clair (Illinois), and lost to creation of Clark.
from Randolph (Ill.)from St. Clair (Ill.)from Clark
3 February 1801 · Ind. Terr., Exec. Journal, 98-100; Pence and Armstrong, 212, 520

Show all 17 changes (12 more)

1790
Knox County created Knox created by Northwest Territory from non-county area; Knox included all of present Indiana, plus parts of present Illinois, Michigan, Ohio, and Wisconsin. 20 June 1790 · Terr. Papers U.S., 3:313
1796
Lost territory Knox lost to creation of Wayne (Northwest Territory, extinct).
to Wayne
15 August 1796 · Terr. Papers U.S., 2:567-568, and 3:447; Pence and Armstrong, 216
1798
Lost territory Knox lost to Hamilton (Ohio) in present Indiana and Ohio.
to Hamilton
22 June 1798 · Terr. Papers U.S., 3:509
1800
Became part of Indiana Knox became a county in Indiana Territory when the United States created Indiana Territory from the Northwest Territory. 4 July 1800 · Terr. Papers U.S., 3:86-88; U.S. Stat., vol. 2, ch. 41 [1800]/pp. 58-59
1801
Gained territory Knox gained from non-county area in Indiana Territory, including parts of present Indiana, Michigan, and Ohio; lost to Randolph (Illinois) and St. Clair (Illinois), and lost to creation of Clark.
from Randolph (Ill.)from St. Clair (Ill.)from Clark
3 February 1801 · Ind. Terr., Exec. Journal, 98-100; Pence and Armstrong, 212, 520
1803
Lost territory Knox lost to Hamilton (Ohio), to non-county area of Ohio, and to creation of Wayne (Indiana Territory, extinct) when the state of Ohio was created from the Northwest Territory and Indiana Territory; Knox eliminated from Ohio.
to Hamilton to Wayne
1 March 1803 · Ind. Terr., Exec. Journal, 114-115; Pence and Armstrong, 218; U.S. Stat., vol. 2, ch. 40 [1802], secs. 1-3/pp. 173-174; Van Zandt, 112
1808
Lost territory Knox lost to creation of Harrison.
to Harrison
1 December 1808 · Ind. Terr. Laws, 1801-1809, ch. 1/pp. 645-646
1809
Lost territory Knox lost to creation of Illinois Territory. 1 March 1809 · Terr. Papers U.S., 16:6-8; U.S. Stat., vol. 2, ch. 13 [1809], sec. 1/p. 514
1811
Lost territory Knox lost to creation of Wayne.
to Wayne
1 January 1811 · Ind. Terr. Laws, 1809-1816, chs. 6, 60/pp. 108-111, 190
1813
Lost territory Knox lost to creation of Gibson and Warrick.
to Gibson to Warrick
1 April 1813 · Ind. Terr. Laws, 1809-1816, ch. 23/pp. 348-350
1814
Lost territory Knox lost to Washington.
to Washington
1 September 1814 · Ind. Terr. Laws, 1809-1816, ch. 5/pp. 526-527
1816
Lost territory Knox lost to creation of Orange.
to Orange
1 February 1816 · Ind. Terr. Laws, 1809-1816, ch. 12/pp. 643-645
1816
Exchanged territory Knox exchanged small areas along the Wabash River with Illinois Territory when the state of Indiana was created from Indiana, Illinois, and Michigan Territories. Knox became a county in the state of Indiana. 11 December 1816 · U.S. Stat., vol. 3, ch. 57 [1816], secs. 1-2/p. 289 and res. 1 [1816]/p. 399; Van Zandt, 115
1817
Lost territory Knox lost to creation of Sullivan; all of Knox north of Indian boundary line reverted to non-county status and became part of Non-County Area 4.
to Sullivan
15 January 1817 · Ind. Acts 1816, 1st sess., ch. 49, secs. 1-2, 5/pp. 205, 207
1817
Lost territory Knox lost to creation of Pike.
to Pike
1 February 1817 · Ind. Acts 1816, 1st sess., ch. 51, secs. 1-2, 8/pp. 208-210
1817
Lost territory Knox lost to creation of Daviess.
to Daviess
15 February 1817 · Ind. Acts 1816, 1st sess., ch. 43, secs. 1-2/p. 192
1842
Lost territory Knox lost small area to Sullivan.
to Sullivan
5 December 1842 · Ind. Rev. Stat. 1843, ch. 2, secs. 2, 26, 28-31, 36-37, 42-44, 61, 67, 77, 80-82, 85-86/pp. 68, 74-81, 84, 86, 88-89

Land and parcels

What the maps cover in Knox

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

Parcels Good enough

Lot lines and tax-map numbers for 29,961 parcels from Indiana Geographic Information Office (IndianaMap). Drawn for tax purposes: usually within a few feet of a survey, but not a survey.
edited 6 October 2026 · checked 15 October 2026
Address points Official

One point per address, 18,284 in all from Indiana Geographic Information Office (IGIO).
edited 8 March 2026 · 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

Knox by the Census

Population

36,282 2020 Census count

Housing units

16,917 2020 Census count

Land area

516 square miles

Water area

8.1 square miles

People per sq mi

70 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 records 812-885-2513from knoxcounty.in.gov · checked 13 October 2026

Permits

Health department: septic and well 812-882-8700from knoxcounty.in.gov · checked 13 October 2026

County government

County government
The official website of Knox County.
knoxcounty.in.gov

See your own lot on these maps

Open Knox 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 Knox County

When was Knox County founded?: Knox County was founded in 1790, and named after Henry Knox.
What is the county seat of Knox County?: The county seat of Knox County is Vincennes.
Is there an online parcel map for Knox County?: Yes. Indiana Geographic Information Office (IndianaMap) publishes a parcel map of 29,961 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Knox County's boundary or name changed?: Knox County was created in 1790. Since then the Atlas of Historical County Boundaries records 16 later changes, chiefly involving Wayne County, Hamilton County and Sullivan County.
Who issues septic and well permits in Knox County?: The county's page on septic systems and wells: Health department: septic and well.
Is my lot in a flood zone?: We do not have flood maps for Knox County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

Nearby