What happened? How did you get a new state?
The game comes with a campaign editor that can handle a lot of the hard work (I downloaded the update to the game specifically to be able to do that - editing the text files isn't difficult, but it is tedious). I just drew a new map for my timeline and plugged it into the game files (the editor can't do that part). Conveniently, my map has 50 states, so I didn't have to add any new states, just move them around. Colorado, for example, was originally Alaska. Sonora was one of the Dakotas, Jacinto was West Virginia. Actually, as you can see, the extra seats in Nebraska and Maine haven't been finished yet so there are a few awkward blobs on the map. But creating new states from scratch is probably going to be a little harder than editing existing ones.
The hardest part is actually working out the politics of the whole scenario. Each state has to be calibrated to at least seem realistic. And obviously something is off with some of my states and/or politicians, because a lot of what went Republican shouldn't be. This election is actually supposed to be Medina's re-election to a second term. I haven't done a serious playthrough with her, so it may not be impossible, but the results so far are not what I was hoping for. I think the biggest hurdle with making Democrats more competitive is the fact that House of Representatives (and therefore the Electoral College) has about 100 more seats, and obviously those extra seats are concentrated in the states that are already more liberal.