MA: Springfield
NY: Albany, Buffalo,Rochester
Oh: Sandusky, Cleavland, Toledo,
IN: Fort wayne
IL: Chicago, Rockford,
WI: Madison, LaCrosse, Eu Claire, Milwaukee
With some fairly minor deviations on the path. (Assuming a fairly straight path that stays in the US, going south of the lakes). Depending on your tolerance for minor deviations from the straightest possible path it could be all or a subset, but not none of those. They are all medium sized or larger cities.
There are ton of small cities too, but the train doesnt have to stop in each one - there's lots of through trains in Europe to that skip towns/cities they pass.