If everything was started from scratch tomorrow, the likelihood of present day California and Texas naturally ending up together in the same nation is pretty much zero, IMHO.
Those two are kept together by pretty much a country-sized version of a Sunken Cost Falacy.
One can't even count on language or culture as a unifying element, otherwise the whole of Latin America would be 2 countries, Brasil & Everybody Else.
It doesn't even need to be alone to gain energy and still works fine with just one or two people who you're close to.
It's the "lot's of people" and the "people I barelly know" that are exhausting.