Illinois - Chicago has been shrinking (though tbf so has the rest of the state). The state has been pretty stagnant politically for a while now, however, that's in large part because Democrats had been able to make up for rural losses with some massive improvements in the Chicago suburbs which seem difficult to replicate again in this decaede. Furthermore, the heavily black South Side of Chicago has been bleeding for quite a while now and generally soi have a lot of the minority communities in the state. There def seem to be some rural communities, especially in the Northern part of the state, in which the GOP has potential to grow. Again, this is really a stretch but not impossible.
Illinois Undercounted in 2020 Census, Actually Grew to 13 Million — The State's Largest Population Ever