Although I have nothing to help you, the other two options you might want to consider regarding migration in general are the canal systems, where people moved goods- -obviously prior to the railroads- -and ferries, i.e, how people crossed rivers, let's say in migrations westward, as well as commerce on the Great Lakes. Personally I find the whole migration topic and movement of populations (specifically the families I am studying) interesting. Families: SURINE/SIRRINE/SARINE, TUSING/TUSSING, SHEARHART