English: Hartland covered bridge - This structure, 390.75 metres long is by far the longest covered bridge in the world. Covered bridges date from the first decade of the 19th century when North American builders began using wooden trusses for long spans and covered them to prevent the truss joints from rotting. After 1840 the Howe truss, which introduced iron tension rods into the truss work, was widely adopted and New Brunswick erected numerous bridges using this technique, among them this one which was built in 1921. Hartland, New Brunswick, Canada Made Explore #299 Aug. 14, 2008