Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Wayne County is a county located in the U.S. state of Illinois. As of 2000, the population was 17,151. Its county seat is Fairfield, Illinois. According to the U.S. Census Bureau, the county has a total area of 716 square miles (1,853 km²), of which 714 square miles (1,849 km²) is land and 2 square miles (4 km²) (0.23%) is water.Wayne County was formed in 1819 out of Edwards County. It is named after Gen. "Mad Anthony" Wayne, an officer in the Revolutionary War and Northwest Indian War.