Stone bridges were strongest, but America, with its scant investment capital and lack of time, was frequently forced to turn to its timber supplies. Flimsy trestles were thrown up in weeks to help the railroads push west. Most of them have long since been replaced, but the one at left, built by the Great Northern Railroad at Hanover, Montana, in 1930, still carries freight. In contrast to its crude complexity, the engaging little shed above enjoys the distinction of being the shortest covered railroad bridge in the world. Built around the turn of the century by the St. Johnsbury & Lamoille County Railroad at Wolcott, Vermont, the ninety-foot span did yeoman service until the line was recently abandoned. The bridge, however, still survives.