Transforming the Upper Midwest into a single economy requires the ability to visit a distant city and return the same day.
That means downtown-to-downtown trips of just two hours; three hours max.
With modern trains, the entire Midwest would be less than three hours from Chicago.

With transit times that short, it would become very practical to spend a fully productive day in another city and still be home in time for dinner.
These trains would also draw our major universities together, allowing them to cooperate more closely and focus on their individual strengths.