Subfloor tunnels during lock construction

Photograph showing a view of the subfloor tunnels having almost reached the east end of the lock chamber and the outflow passages taking shape just below the center of the image.
Abstract/Description: Photograph showing a view of the subfloor tunnels having almost reached the east end of the lock chamber and the outflow passages taking shape just below the center of the image.
Subject(s): Boats and boating
Soo Locks (Mich.)
Date Created: 1912 (approximate)