Iola is the county seat of Allen County, Kansas, United States. The city is situated along the Neosho River in southeast Kansas. As of the 202…Iola is the county seat of Allen County, Kansas, United States. The city is situated along the Neosho River in southeast Kansas. As of the 2020 census, the population of the city was 5,396. It is named in honor of Iola Colborn, the wife of Josiah Colborn, one of the town's founders.