Rush County is a county in the U.S. state of Indiana. In the 2020 United States Census, the population was 16,752. The county seat is Rushville. When the Indiana Territory was granted statehood, 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 o…Rush County is a county in the U.S. state of Indiana. In the 2020 United States Census, the population was 16,752. The county seat is Rushville. When the Indiana Territory was granted statehood, 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 to begin organizing the county's governing structure on June 3, 1822. The act also authorized six townships to cover the county; subsequent growth through the years has caused the number of townships to double. It was named for Dr. Benjamin Rush, one of the signers of the 1776 Declaration of Independence. That same summer the future town of Rushville was platted and laid out.