When was Lee County founded?

Lee County was founded in 1839, formed from Ogle County, and named after Henry Lee III.

What is the county seat of Lee County?

The county seat of Lee County is Dixon.

Is there an online parcel map for Lee County?

Yes. A public source publishes a parcel map of 29,034 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.

Has Lee County's boundary or name changed?

Lee County was created in 1839 from Ogle County. The Atlas of Historical County Boundaries records no boundary change since.

Is my lot in a flood zone?

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

County · code 17103

Lee CountyIllinois

Lee County is in Illinois, with its county seat in Dixon, and was established in 1839.

Founded1839
County seatDixon
Named forHenry Lee III
Land area725 sq mi + 3.8 sq mi water
Population34,145 2020 Census
Parcels mapped29,034 checked 16 October 2026

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

Updated 19 October 2026

Census outline · seat marked

History

Formed in 1839 from Ogle County

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

Lee County was created from Ogle County on February 27, 1839. The county was named after Henry Lee Iii.

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

1839
Lee County created Lee created from Ogle.
from Ogle
27 February 1839 · Ill. Laws 1838-1839, pp. 170-172

Land and parcels

What the maps cover in Lee

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

Parcels Good enough

Lot lines and tax-map numbers for 29,034 parcels. Drawn for tax purposes: usually within a few feet of a survey, but not a survey.
checked 16 October 2026
Address points Missing

No public address points layer found for Lee County yet.
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

Lee by the Census

Population

34,145 2020 Census count

Housing units

14,985 2020 Census count

Land area

725 square miles

Water area

3.8 square miles

People per sq mi

47 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

Lee 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 Lee County.
countyoflee.org

See your own lot on these maps

Open Lee 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 Lee County

When was Lee County founded?: Lee County was founded in 1839, formed from Ogle County, and named after Henry Lee III.
What is the county seat of Lee County?: The county seat of Lee County is Dixon.
Is there an online parcel map for Lee County?: Yes. A public source publishes a parcel map of 29,034 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Lee County's boundary or name changed?: Lee County was created in 1839 from Ogle County. The Atlas of Historical County Boundaries records no boundary change since.
Is my lot in a flood zone?: We do not have flood maps for Lee County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

Nearby