Franklin County is a county located in the eastern portion of the U.S. state of Kansas. Its county seat and most populous city is Ottawa. As of the 2020 census, the county population was 25,996. The county was named for Benjamin Franklin, a founding father of the United States. Formerly it was considered part of the Kansas City metropolitan area, but was re…Franklin County is a county located in the eastern portion of the U.S. state of Kansas. Its county seat and most populous city is Ottawa. As of the 2020 census, the county population was 25,996. The county was named for Benjamin Franklin, a founding father of the United States. Formerly it was considered part of the Kansas City metropolitan area, but was removed in 2013.