The tunnel was built in 1871 by the Midland Railway Line in order to cross the Wallkill Valley. New York, Susquehanna and Western Railway took over control of the tunnel in 1881 when the Midland Railway Line was merged into it.
The tunnel was first referenced as the Backwards Tunnel in 1976 because it was thought that the tunnel should have been wider over the road than over the river. Ogdensburg declared the tunnel a borough historic site in 1991. A flood in 2000 which caused two nearby dams to burst damaged the tunnel. A book was published in 2009 about the history of the tunnel.
Description via Wikipedia