The first settlement in the county was made by Dr. Jacob Holland in 1836, about eight miles southwest of this site. When Missouri became a state in 1821, what is now Sullivan County became part of Chariton County. In 1842, the legislature passed an act to define the boundaries of Highland County, with boundary lines the same as the present boundaries of Sullivan County. In 1844, Highland County was found to contain a population sufficient to permit a full organization. On February 14, 1845, the legislature approved the organization of Sullivan County, dropping the name Highland, in honor of General John Sullivan of the Revolutionary War.