Johnson County is a county located in the U.S. state of Illinois. As of 2000, the population was 12,878. Its county seat is Vienna, Illinois.
History
Johnson County was organized in 1812. It was named for Richard M. Johnson, who was then a U.S. Congressman from Kentucky. In 1813, Johnson commanded a Kentucky regiment at the Battle of the Thames, after which he claimed to have killed Tecumseh in hand to hand combat. Johnson went on to be Vice President of the United States.
