County Formation. When Illinois became a state in 1818, the area that is now Marshall county was part of Bond and Clark counties. As more counties were formed, the area became part of Pike, Sangamon, Putnam, and LaSalle counties. Marshall county was established in 1839 from Putnam county.
Topeka is an incorporated town in Mason County, Illinois, United States. The population was 90 at the 2000 census. Topeka is located at 40Â°19â²48â³N 89Â°55â²52â³Wï»¿ / ï»¿40.33000Â°N 89.93111Â°Wï»¿ / 40.33000; -89.93111 (40.329960, -89.931034). According to the 2010 census, Topeka has a total area of 0.14 square miles (0.36 km 2), all land.
At that time, Shawnee County borders were entirely south of the Kansas River and extended south to include Osage City and Carbondale. The legislature later desired to make Topeka the county seat and moved the borders of the county to their present locations to make Topeka centrally located in the county.