At the close of the War of 1812, the U.S. government set aside tracts of land called the Military Tract, and it was given to the officers and soldiers who had fought in that war. Because Captain Ossian Ross was so honored, he received 320 acres of farm land and moved to Illinois in 1820. Mr. Ross kept 100 acres for a homestead and then platted a town and went about securing a county seat. He named the town Lewistown in honor of his son, Lewis. Lewistown has the honor of being the oldest town (1822) in Fulton County and one of the oldest in the Military.
Mr. Ross donated land for a courthouse, a jail, and a church. In October 1823, the first courthouse of hewn logs was completed at a cost of $500.00. This building served as the courthouse until 1830, when the building seemed inadequate and a new building was erected at a cost of $649.00. Nine years later this building which served as the courthouse was sold to the Methodist Church. The third courthouse was completed in 1839, this time from brick with a stone foundation and was erected at a cost of $9000.00. Newton Walker was appointed to draw plans, make specifications and supervise the construction.