Never built

Eel River Unfinished Bridge (Clay County, Indiana)
An extension of the Southern Indiana to Indianapolis started in 1905 but not finished.
Bridge over Eel River on nothing
Never built

Horse Cove Grand Lake Mystery Bridge (Delaware County, Oklahoma)
According to local, bridge was started but never completed.
Never completed bridge over Grand Lake
Project abandoned

Union Station (Unbuilt) (Polk County, Iowa)
Closed-spandrel arch bridge over Des Moines River on Railroads/Passenger Station
Never built