Cool Valley is a city located in St. Louis County with a population of 1,196 at the time of the 2010 census. Covering no more than 0.47 square miles of land, it has the 28th smallest total area of all the St. Louis county municipalities.
Incorporated as a small town in the fall of 1951, the area grew rapidly in size with a population increase of more than 40 percent — less than 20 years after incorporation. This was also a huge time of expansion for St. Louis County, as many notable northern St. Louis county municipalities began forming throughout the later portion of the 1940s into the 1950s. Cool Valley benefitted from the luxury of prime location being in close range of booming developments of the time, such as the new University of Missouri St. Louis (UMSL) campus.
Cool Valley incorporated towards city status in 1981.
Residents of Cool Valley are served by the Ferguson-Florissant School District.