When the county seat was moved to Williamsport, a log house belonging to the town's proprietor, William Harrison, served as the courthouse starting in July 1829.

In 1832, plans were made for a new building, and in July of that year the construction bid was won by E. W. Jones and Seth Flowers.

The plans called for a new brick building to be constructed in what is now known as "Old Town", the original portion of Williamsport that was on the shores of the Wabash River.

Early on the morning of Sunday, January 20, 1907, the building caught fire and was largely destroyed, though most of the records were saved.

[5] The county purchased two large brass cannons from the United States Government and placed them outside the building, where they still remain.