Valley Park is a city in St. Louis County, Missouri, United States. The population was 6,885 at the 2020 census. Descendants of the Missis…Valley Park is a city in St. Louis County, Missouri, United States. The population was 6,885 at the 2020 census. Descendants of the Mississippian culture still had a settlement along the Meramec River in the mid-18th century, until the Native Americans were pushed out by colonial French and German immigrant farmers in the 1760s. The developing village over time was known as Nasby, Sulphur Springs, Quinette, Meramec, and finally Valley Park by circa 1890. It had one of the first post offices established in St. Louis County. It developed as a railroad hub for the Missouri Pacific and St. Louis-San Francisco rail lines.