This image is of the Mackinac Bridge between the Lower and Upper Peninsulas of Michigan, as seen from the center of the driving deck, looking at the two towers nicely framed in the center.

The caption states:
THE MACKINAC BRIDGE
Here the roadway grid of the bridge is receiving a coat of green paint, replacing the familiar orange prime cost which most bridges have. The two men on the cable are painters whose job is to paint the “suspenders” which support the roadway. They work downward on the suspenders to the roadbed, and then walk back up the cable to the next suspender to be painted. It’s a long walk. – Photo by Lucy Gridley

–The cars seen in the photo strongly indicate that this picture is from the 1950s.