This image shows one of the brides along the trail leading the the Lake of the Clouds, located in Porcupine Mountains State Park, in the Upper Peninsula of Michigan.
The caption shown reads:
Trail to Lake of the Clouds  N861
Porcupine Mts. State Park, Mich
–Since the park was established in 1945, and this picture is dated 1948, the bridge shown is no more than a few years old at this time. Such trail bridges are regularly replaced and upgraded as they decompose.