During the 18th century, several European colonial settlements were established in the area that would become St. Louis County. French colonists moved from east of the Mississippi River after France ceded territory to Great Britain after losing the Seven Years' War. It also ceded much of its territory west of the River to Spain.
during the 18th century several european colonial settlements were established in the area that would become st louis county french colonists moved from east of the mississippi river after france ceded territory to great britain after losing the seven years' war it also ceded much of its territory west of the river to spain