Book excerpt: They hover over rivers and lakes and valleys and railroad tracks and even parts of oceans. They can be beautiful and they can be ugly. But most of all, they need to be safe. They are the bridges of the United States. And more than 50,000 of them are in poor condition. Read all about American bridges in need of repair in this book. Learn about the ones that have collapsed and the ones that remain open despite remaining in bad shape. The interesting stories here gives readers a tour of bridges both famous and obscure around the United States.