Ogle County, which was organized in 1836, included the territory occupied by the present Lee County with the county seat being located at Dixon's Ferry.
The territory necessary to form Lee County was detached from Ogle County in 1839 and commissioners appointed by the Illinois Legislature designated Dixon as the county seat. "Father" John Dixon was instrumental in the formation of both Lee County and the selection of Dixon as the county seat town.
He donated 80 acres of land to be sold at auction to raise funds necessary to construct a building and had also deeded to the county the block square parcel of land on which the present Old Lee County Court House now stands.
The original brick court house was completed in 1840 for $7,610. On the northeast corner of E. Third and Ottawa Ave a jail building was constructed of hewed logs on a stone foundation at a cost of $1,495. The total cost of the 1840 Lee County Court House building, including the jail facility, was $9,105.
The 1840 Court House, several times remodeled and enlarged, stood and was used until March, 1900, when it was demolished to make way for construction of the present structure. The newer court house building cost $103,394.94 for the general construction. Additional costs for metal and wooden furniture, grading, street retaining walls and sidewalks added another $20,808.84 to the building, making a total of $123,203.78 for the entire fully equipped building.
Excerpt from HISTORY OF LEE COUNTY by Frank E. Stevens, http://www.archive.org/stream/historyofleecoun_01stev#page/n7/mode/2up
"Odd dates figured conspicuously in the early affairs of Lee County. On Friday, The 13th of September,  Lee County began business, and who shall say she ever has met an unlucky or unpropitious minute! And who shall say she has failed to keep pace in the race with her 101 sister counties!"