[WorldMaker]

> But establishing a system to handle regional planning would require crossing state boundaries in six of those cases.

6 of 11 is more than half of your examples. That alone seems to suggest there would be efficiencies in federally-supervised planning simply to cross-cut inter-state concerns. (Such as with roads, the use of "inter-state" there is not an accident.)

Scrolling further through the list of CSAs the ones between a million people and seven million that are multi-state seem too often to be the least well served by public transportation access today compared to their peers, and that doesn't seem to be a coincidence.