Putnam County is the least extensive county in the U.S. state o...wikipedia - 15 Nov 2020
Putnam County is the least extensive county in the U.S. state of Illinois. According to the 2010 census, it had a population of 6,006. The county seat is Hennepin. The county was formed in 1825 out of Fulton County and named after Israel Putnam, who was a general in the American Revolution. Putnam County is part of the Ottawa, IL Micropolitan Statistical Area.