There is no way GOOD way to divide the map up.
Some otherwise good people would have to lose.
Chicago/Detroit... Philly/Trenton.. DC/Baltimore are all good choices but they are hundreds of miles apart from each other.
And NYC would fit in there somewhere. and then there is New England?
Another huge issues would be coastal land and more specifically ports. What are now huge cities started around waterways and ports.
Anyhow, the map as it is now, is quite scattered and slicy dicy.
Who would get the military?