From the record
“The Imes Bridge is a wooden covered bridge in Madison County, Iowa. Built in 1870, it was originally located over the Middle River.”
Wikipedia article Imes Bridge, CC BY-SA 4.0.
One of 55 National Register listings published here for Madison County · listed in 1979 · category: Structure · built in 1870.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service