Blue Mound is a city in Linn County, Kansas, United States. As of the 2020 census, the population of the city was 219. Blue Mound was laid out i…Blue Mound is a city in Linn County, Kansas, United States. As of the 2020 census, the population of the city was 219. Blue Mound was laid out in 1882. It was named by its first postmaster, John Q. Adams, because its elevation is said to look blue from a distance.