Covered Bridges of Ohio. 290 color and B&W photographs of 145 of Ohio's Wooden Truss Covered Bridges including the longest covered bridge in the United States. GPS data provided for locating each bridge.. Most of our Covered Bridges are over 100 years old. Local craftsmen built these structures using hand tools. That these bridges have survived this long bearing loads never dreamed of by the designers is a testament to the skill of the builders. This skill has virtually disappeared. They represent an aspect of our Nations heritage that we should make every effort to preserve.