The midwest has the following top 20 CS schools: Illinois (tied for #1), Michigan, Wisconsin, Purdue, maybe Carnegie Mellon (also tied for #1).
In addition, the midwest also has the following universities which are top institutions in some fields: Northwestern, University of Chicago, Washington University in St. Louis, Ohio State, Minnesota. I'm probably leaving out at least one Chicagoland school. Indiana is also quite good for CS, but is just not big enough to show up at the top of the rankings.
The problem is not a lack of top-tier universities. The problem, especially in Computer Science, is that everyone leaves after university. E.g., here's a map from CMU (page 4): https://www.cmu.edu/career/documents/2017_one_pagers/scs/BS_...
From CMU, only 2% go to the midwest while 67% go to the west coast and 17% go to the northeast. Similarly, from UW-Madison, only about half stay in the midwest: https://dataviz.wisc.edu/views/FirstDestinationSurvey_0/Empl...
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US News 20 CS schools by state/region (note that UIUC is now in the tie for top):
1. Carnegie Mellon (Pittsburgh, regionally ambiguous)
1. MIT (New England/Northeast)
1. Stanford (California/West Coast)
1. Berkeley (California/West Coast)
1. UIUC (Great Plains or maybe Upper Midwest/Midwest)
5. Cornell (New England/Northeast)
6. UW (PNW/West Coast)
6. Georgia Institute of Technology (South)
8. Princeton (New England/Northeast)
8. UT-Austin (Texas/South)
10. California Institute of Technology (California/West Cost)
11. University of Michigan--Ann Arbor (Upper Midwest/Midwest)
13. UCLA (California/West Coast)
13. Wisconsin (Upper Midwest/Midwest)
13. Harvard (Northeast)
16. UCSD (California/West Coast)
16. University of Maryland--College Park (Mid-Atlantic/Northeast)
16. University of Pennsylvania (Mid-Atlantic/Northeast)
19. Purdue (Midwest)
20. Rice University (Texas/South)
20. USC (California/West)
20. Yale (New England/Northeast)
20. Amherst (New England/Northeast)