Aerial survey project no. 77S-37 was flown on April 22 and April 26, 1977. These photos are a verbal scale of 1"=400'. The flight lines provide coverage for highway 169 and bridge 4377 over the Watonwan River and bridge 4983 over the Chicago and North Western Railroad. ASP No. 77S-37 includes index sheet 1. The index indicates the focal length is 152.46mm but the air photos read 152.47mm.
