[2] When the Indiana Territory was granted statehood (December 20, 1816), there were no settlers on the lands of the future Rush County.

However, this changed quickly, and by 1821 the newly founded settlements were desirous of being organized into a county unit.

Accordingly, the state legislature passed an act dated December 31, 1821, which authorized Rush County, effective April 1, and further authorized the first commissioners (pro tem) to begin organizing the county's governing structure on June 3, 1822.

[4] That same summer (1822) the future town (and county seat) of Rushville was platted and laid out.

In the 1820s the low rolling hills of Rush County were generously covered with trees, usually walnut and sugar maples.

[6] The Big Blue River drains the upper part of the county, flowing to the southwest.

[7][8] The terrain's highest point (1,135 feet/346 m ASL) is an isolated rise at the county's east boundary, 1.4 miles (2.3 km) SSW of Glenwood.

The commissioners execute acts legislated by the council, collect revenue, and manage the county government.