Photo scanned by Internet Archive Book Images
View this photo at archive.org
BH Photo #366036
Do your photographs mention the company that constructed the bridge at all?
Also there's a county historical society/museum in Kelso, from the looks of it: http://www.co.cowlitz.wa.us/museum/
Finished bridge, one of several pictures.
I have about 10 pictures of the construction of this bridge. My grandfather was a civil engineer and worked on this project. I would love to have the pictures go to a historical society. Do you have any suggestions?