[3] The relatively small number of surviving bridges is due to deliberate replacement, neglect, and the high cost of restoration.

[4] Surviving covered bridges often attract touristic attention due to their rarity, quaint appearance, and bucolic settings.

[9] In 1847, American engineer Squire Whipple published the first correct analysis of the precise ways that a load is carried through the components of a truss,[12] which enabled him to design stronger bridges with fewer materials.

[2] The first documented was the Permanent Bridge, completed in 1805 to span the Schuylkill River in Philadelphia.

[5] The longest covered bridge ever built was constructed in 1814 in Lancaster County, Pennsylvania, and spanned over a mile in length, but was destroyed by ice and flooding in 1832.

The bridges also became obsolete because most were single-lane, had low width and height clearances, and could not support the heavy loads of modern traffic.

[20] The tallest (35 feet high), built in 1892, is the Felton Covered Bridge, just north of Santa Cruz, California.

[22] Relative to the rest of North America, Quebec was late in building covered bridges, with the busiest decade for construction being the 1930s.

[19] The last agricultural colony was founded in 1948, and the last bridge was built by the Ministry of Colonisation in 1958 in Lebel-sur-Quévillon.

Roofed, rather than covered bridges, have existed for centuries in southern Europe and Asia.