Why Covered Bridges:
They protect exposed wooden superstructures from rot resulting from exposure to the elements (rain, sleet, snow, and blazing sun).
An uncovered wooden bridge's life span would be 15-20 years; but with a roof and sides, one would last as long as a hundred years.
Wooden bridges prevented heavy snows from covering and/or blocking passage.
Barn-like appearance soothed animal fears of bridge crossing (prevented horses from bolting).
Covered bridges protected travelers from the sun.
Often were built by farmers in the form of a bard-raising; hence, they had a barn-like outward appearance, but utilized several different truss systems. TRUSS: triangular system of timbers designed so that each timber helps support the others; together, they distribute the weight and stress over the span of the structure.
In 1805, the first American covered bridge was built in Philadelphia, PA, across the Schuylkill River, with 3 spans and 550' long. The first covered bridge in NC was built across the Yadkin River near Salisbury, in 1818, by a local plantation owner who used Ithiel Town's lattice truss. During the 19th century, there were 1000s of covered bridges throughout the United States and 100s in North Carolina.