On the other hand, I really like the idea of splitting apart the country in a way that frees most of us from a large enough number of the people who are holding us back. I don't think that's possible to do in a fine-grained way. It only makes sense if done for some large contiguous regions. And the states in the southeast who actually did try to break away a few generations ago seems like an obvious way forward with that.
Here is another look at some of the natural regions within the country: [1]
I'm also aware that changing the voting systems we use holds a lot of promise for some of the same underlying problems we're talking about, and am completely open to that as an alternative to, or in addition to, my suggestion to break up the country. But that too seems very difficult politically.
[1] https://www.nytimes.com/2016/04/17/opinion/sunday/a-new-map-...
I'm not a political scientist, but at some point the increasingly larger 60% of the population is going to take this country back. I hope they're able to do it without a war.
For example, take a useful look at CityLab's Congressional Density Indicator [1]. There are zero "pure urban" districts that are represented by Republicans, regardless of the state (red, blue, purple), and there are nearly none among the "urban-suburban mix" districts (again regardless of state).
Viewed through yet another lens, by percentage of landmass, Alabama is more is more "blue" than Illinois and Oregon [2]. Your characterization could use a little more thought and refinement.
[0] https://www.niskanencenter.org/wp-content/uploads/2019/09/Wi... (see section beginning page 12)
[1] https://www.citylab.com/equity/2018/11/citylab-congressional...
[2] https://www.nytimes.com/interactive/2018/upshot/election-201...