Chillicothe is a city in the U.S. state of Ohio and the county seat of Ross County. It was also the first and third capital of Ohio. The municipality is located in southern Ohio along the Scioto River. The name comes from the Shawnee name Chalahgawtha, meaning "principal town. " Plotted by General Nathaniel Massie on his own land. The population was 21,796 at the 2000 census. According to the U.S. Census 2008 estimate, Chillicothe has a population of 22,296, while the Columbus-Marion-Chillicothe, OH Combined Statistical Area has 2,002,604 people. The city is the largest in Ross County, and the center of the Chillicothe Micropolitan Statistical Area (as defined by the United States Census Bureau in 2003).