Editing Truss bridge (section)

==United States==
In the [[United States]], because wood was in abundance, early truss bridges would typically use carefully fitted timbers for members taking compression and iron rods for [[tension member]]s, usually constructed as a [[covered bridge]] to protect the structure. In 1820, a simple form of truss, [[Lattice truss bridge|Town's lattice truss]], was patented, and had the advantage of requiring neither high labor skills nor much metal. Few iron truss bridges were built in the United States before 1850.

Truss bridges became a common type of bridge built from the 1870s through the 1930s. Examples of these bridges still remain across the US, but their numbers are dropping rapidly as they are demolished and replaced with new structures. As metal slowly started to replace timber, [[wrought iron]] bridges in the US started being built on a large scale in the 1870s. Bowstring truss bridges were a common truss design during this time, with their arched top chords. Companies like the [[Massillon Bridge Company]] of [[Massillon, Ohio]], and the [[King Bridge Company]] of [[Cleveland]], became well-known, as they marketed their designs to cities and townships.

The bowstring truss design fell out of favor due to a lack of durability, and gave way to the Pratt truss design, which was stronger. Again, the bridge companies marketed their designs, with the Wrought Iron Bridge Company in the lead. As the 1880s and 1890s progressed, [[steel]] began to replace wrought iron as the preferred material. Other truss designs were used during this time, including the camel-back. By the 1910s, many states developed standard plan truss bridges, including steel Warren [[half-through|pony]] truss bridges.

In the 1920s and 1930s, [[Pennsylvania]] and several states continued to build steel truss bridges, using massive steel through-truss bridges for long spans. Other states, such as [[Michigan]], used standard plan concrete girder and beam bridges, and only a limited number of truss bridges were built.