Doon is a city in Lyon County, Iowa, United States, along the Rock River. The population was 619 at the time of the 2020 census. The BNSF R…Doon is a city in Lyon County, Iowa, United States, along the Rock River. The population was 619 at the time of the 2020 census. The BNSF Railway passes through Doon. Located on a plateau on the eastern bank of the Rock River, the city was named after the River Doon in Scotland, made famous as the subject of Robert Burns' poem, "The Banks O' Doon". Founded by G. W. Bowers and A. H. Davison on September 6, 1889, the railway town was connected first by the Rock Valley Railway, followed by the Iowa & Dakota Railroad. The city was incorporated on March 8, 1892.