I found this area in North-Central Marion County where there are three bridges within a mile of each other. That's not so rare, but these each cross a separate body of water. This one crosses Grassy Creek.
DO NOT PARK ALONG HIGHWAY "A"
Park at listed coordinates (N39 54.920 W091 37.404) along County Road 150
Also, the stamp and ink pad are part of the Cache. DO NOT REMOVE!