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County · code 17037

DeKalb CountyIllinois

DeKalb County is in Illinois and was created in 1837 with Sycamore as its county seat. The county was named after Johann de Kalb.

  • Founded1837
  • County seatSycamore
  • Named forJohann de Kalb
  • Land area631 sq mi + 3.3 sq mi water
  • Population100,420 2020 Census
  • Parcels mapped45,411 checked 15 October 2026
Open the free map Click any parcel in DeKalb County: acreage, parcel id, address and who publishes the map. No sign-in.

Updated

KaneBooneKendallLeeLaSalleOgleWinnebago Sycamore Census outline · seat marked

Where it is

DeKalb 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 CountyDe Witt CountyDouglas CountyDuPage CountyEdgar CountyEdwards CountyEffingham CountyFayette CountyFord CountyFranklin CountyFulton CountyGallatin CountyGreene CountyGrundy CountyHamilton CountyHancock CountyHardin CountyHenderson CountyHenry 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 CountyDeKalb County DeKalb
Counties of Illinois · DeKalb highlighted

History

Formed in 1837 from Kane County

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

DeKalb County was created from Kane County on May 1, 1837.

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

  1. 1837
    DeKalb County created De Kalb created from Kane.
    from Kane
    · Ill. Laws 1836-1837, pp. 96-100

Land and parcels

What the maps cover in DeKalb

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

DeKalb by the Census

Population
100,420 2020 Census count
Housing units
41,311 2020 Census count
Land area
631 square miles
Water area
3.3 square miles
People per sq mi
159 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

GIS and maps

County government

See your own lot on these maps

Open DeKalb 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 DeKalb County

When was DeKalb County founded?
DeKalb County was founded in 1837, formed from Kane County, and named after Johann de Kalb.
What is the county seat of DeKalb County?
The county seat of DeKalb County is Sycamore.
Is there an online parcel map for DeKalb County?
Yes. DeKalb County publishes a parcel map of 45,411 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has DeKalb County's boundary or name changed?
DeKalb County was created in 1837 from Kane County. The Atlas of Historical County Boundaries records no boundary change since.
Who issues septic and well permits in DeKalb County?
The county's page on septic systems and wells: Directions.
Is my lot in a flood zone?
We do not have flood maps for DeKalb 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