Theodore Burr bragged that the wooden arch-truss bridge over the Susquehanna River that he designed in 1815 contained "the greatest [arch] in the world . . . at three hundred and sixty feet four inches." It was certainly one of the most difficult bridges in America to build. At the spot Burr chose, the Susquehanna was swift, almost one hundred feet deep, and subject to ice floes during the spring thaw. Instead of working in the dangerous main channel Burr's laborers constructed the bridge's central arch in upright sections at a spot a quarter-mile downstream, then used the frozen river of January 1815 to swing it upstream and raise it into place. Unfortunately, the river was not entirely frozen, and blocks of ice mixed with slush had stacked up at the narrows to a depth of sixty to eighty feet where the bridge piers stood ready for...