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County · code 17073

Henry CountyIllinois

Henry County is a county in Illinois, formed in 1825 and seated in Cambridge.

  • Founded1825
  • County seatCambridge
  • Named forPatrick Henry
  • Land area823 sq mi + 2.6 sq mi water
  • Population49,284 2020 Census
  • Parcels mapped31,932 checked 16 October 2026
Open the free map Click any parcel in Henry County: acreage, parcel id, address and who publishes the map. No sign-in.

Updated

StarkKnoxRock IslandWhitesideBureau Cambridge Census outline · seat marked

Where it is

Henry on the map of Illinois

Illinois has 102 counties and county equivalents, each with its own records office. Shapes with a page are links.

Adams CountyAlexander CountyBond CountyBoone CountyBrown CountyBureau CountyCalhoun CountyCarroll CountyCass CountyChampaign CountyChristian CountyClark CountyClay CountyClinton CountyColes CountyCook CountyCrawford CountyCumberland CountyDeKalb CountyDe Witt CountyDouglas CountyDuPage CountyEdgar CountyEdwards CountyEffingham CountyFayette CountyFord CountyFranklin CountyFulton CountyGallatin CountyGreene CountyGrundy CountyHamilton CountyHancock CountyHardin CountyHenderson CountyIroquois CountyJackson CountyJasper CountyJefferson CountyJersey CountyJo Daviess CountyJohnson CountyKane CountyKankakee CountyKendall CountyKnox CountyLake CountyLaSalle CountyLawrence CountyLee CountyLivingston CountyLogan CountyMcDonough CountyMcHenry CountyMcLean CountyMacon CountyMacoupin CountyMadison CountyMarion CountyMarshall CountyMason CountyMassac CountyMenard CountyMercer CountyMonroe CountyMontgomery CountyMorgan CountyMoultrie CountyOgle CountyPeoria CountyPerry CountyPiatt CountyPike CountyPope CountyPulaski CountyPutnam CountyRandolph CountyRichland CountyRock Island CountySt. Clair CountySaline CountySangamon CountySchuyler CountyScott CountyShelby CountyStark CountyStephenson CountyTazewell CountyUnion CountyVermilion CountyWabash CountyWarren CountyWashington CountyWayne CountyWhite CountyWhiteside CountyWill CountyWilliamson CountyWinnebago CountyWoodford CountyHenry County Henry
Counties of Illinois · Henry highlighted

History

Formed in 1825 from Fulton County

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

Henry County was created on January 13, 1825, from Non-County Area 5 attached to Fulton County and named after Patrick Henry. The county experienced several boundary changes in its early years, losing land to the creation of Jo Daviess County in 1827 and Whiteside County in 1836, while gaining territory from Jo Daviess and Putnam counties in 1831. Henry County was fully organized on June 19, 1837, when it was detached from Knox County.

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

  1. 1825
    Henry County created Henry created from Non-County Area 5 attached to Fulton.
    from Fulton
    · Ill. Laws 1824-1825, pp. 85-87, 92-96
  2. 1827
    Lost territory Henry lost to creation of Jo Daviess.
    to Jo Daviess
    · Ill. Rev. Code 1826-1827, pp. 117-118
  3. 1831
    Gained territory Henry gained from Jo Daviess and Putnam, lost to Knox; Henry attached to Knox "for all judicial and other purposes."
    from Jo Daviessfrom Putnamfrom Knox
    · Ill. Laws 1830-1831, pp. 54-57, 62-63
  4. 1836
    Lost territory Henry lost to creation of Whiteside.
    to Whiteside
    · Ill. Laws 1835-1836, pp. 273-278
  5. 1837
    Changed Henry fully organized, detached from Knox.
    Knox
    · Ill. Laws 1836-1837, pp. 90-91
Show all 9 changes (4 more, mostly small adjustments)
  1. 1825
    Henry County created Henry created from Non-County Area 5 attached to Fulton.
    from Fulton
    · Ill. Laws 1824-1825, pp. 85-87, 92-96
  2. 1827
    Lost territory Henry lost to creation of Jo Daviess.
    to Jo Daviess
    · Ill. Rev. Code 1826-1827, pp. 117-118
  3. 1831
    Gained territory Henry gained from Jo Daviess and Putnam, lost to Knox; Henry attached to Knox "for all judicial and other purposes."
    from Jo Daviessfrom Putnamfrom Knox
    · Ill. Laws 1830-1831, pp. 54-57, 62-63
  4. 1836
    Lost territory Henry lost to creation of Whiteside.
    to Whiteside
    · Ill. Laws 1835-1836, pp. 273-278
  5. 1837
    Changed Legislature authorized creation of Coffee (proposed) from Henry, Knox, and Putnam, dependent on local referendum that failed (no change).
    CoffeeKnoxPutnam
    · Ill. Laws 1836-1837, pp. 86-88
  6. 1837
    Boundary clarified Boundary between Henry and Knox was clarified (no change).
    with Knoxno change
    · Ill. Laws 1836-1837, p. 89
  7. 1837
    Changed Henry fully organized, detached from Knox.
    Knox
    · Ill. Laws 1836-1837, pp. 90-91
  8. 1840
    Changed Legislature authorized Stark to gain from Henry all of township 14 north, range 5 east; and parts of township 14 north, range 4 east, and township 15 north, ranges 4 and 5 east, dependent on local referendum that failed (no change).
    Stark
    · Ill. Laws 1839-1840, spec. sess., pp. 62-63
  9. 1849
    Changed Legislature authorized Stark to gain from Henry a) all of township 14 north, range 5 east, or, b) just the southern half thereof, dependent on local referendum that failed (no change).
    Stark
    · Ill. Laws 1849, 1st sess., gen., pp. 55-56

Land and parcels

What the maps cover in Henry

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

Henry by the Census

Population
49,284 2020 Census count
Housing units
22,211 2020 Census count
Land area
823 square miles
Water area
2.6 square miles
People per sq mi
60 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

Zoning and code

County government

See your own lot on these maps

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Questions

Common questions about Henry County

When was Henry County founded?
Henry County was founded in 1825, formed from Fulton County, and named after Patrick Henry.
What is the county seat of Henry County?
The county seat of Henry County is Cambridge.
Is there an online parcel map for Henry County?
Yes. Henry County publishes a parcel map of 31,932 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Henry County's boundary or name changed?
Henry County was created in 1825 from Fulton County. Since then the Atlas of Historical County Boundaries records 4 later changes, chiefly involving Jo Daviess County, Knox County and Putnam County.
Is my lot in a flood zone?
We do not have flood maps for Henry 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