The Bookstore At The End of America, by Charlie Jane Anders

This is a very modern-day allegory in which California has split from the rest of the United States, now known as America.  The split must be somewhat amicable, because America does not thoroughly invoke the current right wing border fetish--the protagonist's bookstore sits on the border, with one side in each place, and with some navigation one can cross over.  The proprietor finds things to like and dislike about both sides, and they seem economically tied.  But a water war breaks out, and all the propaganda leading up to it is making the respective citizens hate those caricatures of each other.  But they must shelter together.

Not really a new idea, but in the end I think a very necessary one in these times, and Anders handles it very gracefully.