When Missouri became a state in 1821 , St. Louis County was created from the boundaries of the former St. Louis subdistrict of the Missouri Territory ; St. Louis city existed within the county .
Was not coterminous with St. Louis .
When Missouri became a state in 1821 , St. Louis County was created from the boundaries of the former St. Louis subdistrict of the Missouri Territory ; St. Louis city existed within the county but was not coterminous with it .