I visited the setting of this film
Winterset Iowa
I saw the Roseman Bridge, Holliwell Bridge, Cedar Covered Bridge. Not far from there, you can see the John Wayne Museum.
It's beautiful out there. very rural and scenic. The roads are all unpaved and dusty though, and you cannot drive over the covered bridges the way they do in the movies (i.e. the bridges are closed to vehicular traffic). But you can stop right in front of the bridge and walk around and inside it.