Out of use since the ’50s, I suppose. Limestone TN.
In southwest Virginia, Skagg’s Hole tunnel is on the CSX line coming down from Elkhorn City. This is looking north at the trestle crossing the Russell Fork River. The trestle comes 11′ into the tunnel itself. Just to the right and 30′ down, there’s a wide, deep point in the river. I think this feature is the actual “Skagg’s Hole”.