The Lincoln Highway Association has a zoomable, detailed, nationwide overlay on Google Maps of the 1913 Lincoln Highway and some subsequent iterations.
I do see one potential issue in Iowa related to the railroad crossing west of West Side, but there are some clarifications/corrections to my earlier thoughts, including some stubs in Loveland that were there before former IA 183 hugged the railroad closer at a curve, and the Honey Creek Cut.
Now if only I knew how to create a Google Map that used that many points, lines, and details.