Putnam County is a county located in the U.S. state of Indiana. As of the 2020 United States Census, the population was 36,726. The county seat is Greencastle. The county was named for Israel Putnam, a hero in the French and Indian War and a general in the American Revolutionary War. The county was created in 1821 and organized in April 1822.

Owen County is a county in the U.S. state of Indiana. In 1920 the United States Census Bureau calculated the mean center of U.S. population to fall within this county. As of the 2020 United States Census, it had a population of 21,321. Its county seat is Spencer.