In the 1830s, the railroad boom started a new era in the building of railroad bridges pushing engineers to build incredible bridges with timber trestles that have become synonymous with the era.
Timber trestles were one of the few railroad bridge forms that did not develop in Europe. The reason was that in the United States and Canada cheap lumber was widespread and readily available in nearby forests. The Pacific Northwest of the U.S. and the province of British Columbia, Canada became the central region for hundreds of logging railroads whose bridges were almost all made of timber Howe trusses and trestles.
More info / source: vintag.es