The northern endpoint of Missouri 122 is at Van Meter State Park, in Saline County. Missouri 122 is a spur route between the park and Missouri 41. As is typical for spur routes into state parks, the endpoint of the route that's in the state park isn't marked as such. The No Outlet sign might give something of a hint, though.
The park contains the remains of a village occupied by the American Indian tribe for which Missouri is named.