All of these trips are currently frequently taken by car because flying is a nuisance and takes a lot longer than just the flight duration itself.
https://news.ycombinator.com/item?id=14679127
I don't dispute that there are pockets of the US that would be well-served by rail. Maybe SEA-PDX is one of them! Note, though, that neither Seattle nor Portland are in the top 10 economically most important US cities.
I'm not anti-train. I love HSR. I wish we had more of it. But I think there's a solid reason that we don't.
MPLS-Chicago has never really resonated with me, but there are some straight north south lines that I think make a lot of sense ...
Duluth-MPLS-DesMoines-KCMO would make a lot of sense.
Cheyenne-FortCollins-Denver-ColoSprings-Pueblo ... that would make a lot of sense.
Any conversations of car-vs-train have to account for the linear scaling cost compared to loading up 4+ people and/or a bunch of stuff in a car.