County Bridge in New Hampshire, USA

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A bridge built to last. A bridge built to last

The County Bridge has offered a picturesque passage over the Contoocook River in the US state of New Hampshire since 1937. Why build a covered bridge? In a word, longevity. The roof and walls help protect the timber supports from rot. By comparison, an uncovered wooden bridge lasts an average of 20 years, while the covered variety can reach 100 years or more.

But even their durable reputation couldn't withstand the drive toward faster travel - trains, cars, lorries and the heavier loads that came with them. As iron and then steel replaced timber as the bridge-building material of choice, covered bridges gradually went the way of the horse and cart that used to cross them. Out of about 12,000 covered bridges that were built in the US, only 750 remain today - a quarter of which can be found in the state of Pennsylvania.