In order to help me understand population distribution in Minnesota, I made a map of all cities with populations above 5000 (cribbed from Wikipedia's list).
View Minnesota cities over 5,000 (2010 census) in a larger map
(I definitely recommend clicking the link to view larger.)
I've been trying to use it to make a map of the existing rail routes that could connect these cities together, but I've been getting a bit stymied limitations in Google Maps' "My Maps" functionality: As my line-drawing connects more points together, Google appears to be reducing the number of lines that can appear on a single page. As a result, my maps end up looking weird because only some of what I draw can be viewed at the same time. Very frustrating—Apparently I need to be less anal about getting every detail of the routes and be more loose about how closely I follow tracks.
Someday I may figure out Google Fusion Tables and how they can work with Google Maps, but my brain is not happy when I try to wrap it around that subject.
Anyway, it's clear that these communities don't really line up with Interstate highways. I think what strikes me most, however, is how many highways have been built to communities that are much smaller than 5,000.
Oh, and while I'm having trouble getting maps to work nicely, I'll just note that nearly all of these cities have rail connections—they don't always go in directions that make sense for movement of people, but a passenger rail network that reaches 90% of these communities could be accomplished without building very much "new" stuff. A relatively small amount of new track (say, 100 miles or so) could make such a system very well interconnected and much more suitable for passenger use. (The system is currently optimized for freight, which doesn't care if it gets sent 40+ miles out of the way before reaching a destination.)