I own the property North of the original Lincoln Highway. 5th generation.
Do you have any info on this picture if it is looking East or West, and if it is the bridge over the old river bed, or Brown’s ditch ( which is now the Wapsi )?
I don’t have any information on that on hand, however I do know of an organization that might help you there- the Lincoln Highway Group, which you can find on facebook. Other option is to visit the HB Weekend in Iowa this August. There, you might be lucky and meet up with some people who may help you there. I’ll be there as well. Good luck on the research!