Charles M. Spofford of the Boston firm Fay, Spofford & Thorndike designed the 1929 Lake Champlain Bridge, the first American highway bridge to use a continuous truss design to create a curving transition between the deck approach spans on either side of the lake and the arched through span over the navigation channel. The bridge set a precedent for continuous truss bridge design in the decades that followed, and in 2009 Spofford's engineering innovations were recognized when it was listed on the National Register of Historic Places. Its pier concrete contained approximately 20,000 tons of iron ore tailings and crushed ore from the Witherbee Sherman Company mines, brought from Mineville, New York, on the Lake Champlain and Moriah Railroad about nine miles away, because Spofford's research indicated the tailings increased the concrete's strength. Believing the durable mix and its underwater performance made extra protection unnecessary, he did not reinforce the piers with steel or armor them with granite. Because lake bridges were very rare in 1929 and the shearing forces of lake ice were unknown and untested, the unprotected piers later developed surface deterioration and cracking, and the bridge was demolished in 2009 because of safety concerns. Engineers for the 2011 bridge applied lessons from the earlier structure by reinforcing the new piers with steel and armoring them with granite to protect them from the thermal expansion of the lake's ice sheet.