In the midwest, many urban centers are very nonwhite, and will likely have some kind of liberal-pseudo independent democracy. The big thing that midwest power structures would be based around are highways. I would expect that some kind of loose city-states might form, with those states providing protection, ect for the surrounding farms. A lot of nukes are in the central north and midwest, so I would expect that some smaller states would have those weapons. Whatever happens in the midwest would have a big impact on everywhere else, and the crops and nukes would make it an enticing area for early capture by military groups.