St. Louis Region
Castlewood is a state park inside the county map
Castlewood State Park is in western St. Louis County, but park rules, trails, advisories, and reservations come from Missouri State Parks.
Castlewood State Park sits in western St. Louis County along the Meramec River, but the name on the rulebook is Missouri State Parks. A county map can help you place it. It cannot tell you the current trail note, reservation link, advisory, or state-park rule.
That split is the one to remember before a weekend plan. Castlewood questions about trails, park maps, reservations, and state-park rules belong with Missouri State Parks. Nearby county roads, county parks, and other local services stay in the St. Louis County lane.
For a resident searching by county, Castlewood is a good reminder that location and management are not the same thing. The park is local to St. Louis County, but it is run as a state park.
References
Where this fits: this note belongs to St. Louis County. See every local note for the county on its page.