This is a sign at the start of the "Via Concreta" on the ascent of Taum Sauk Mountain, the Rooftop of Missouri. The summit is maybe 150 yards away on this obviously-challenging route.
Check out the time required to Johnson's Shut-Ins -- ten hours for 13 miles, downhill. They don't want you taking any unnecessary risks.
Actually it would be longer right now because the route was destroyed by the Taum Sauk Reservoir Disaster of 2005
. It's being rebuilt -- call the park before planning a hike connecting these two state parks.