Datum Earth

Datum Earth is the only known one of the Long Earths where Humans evolved; it can be considered as our Earth in the The Long Earth series. Over the course of the first two books, it passes from the dominant influence in colonising the Long Earth to being the distant colonising power that the Steppers inevitably rebel against. Following a calamity lampshaded in The Long War - namely the eruption of the volcanic caldera under Yellowstone - Datum Earth eventually realises the relationship is changed and it is now pretty much dependent on the colony worlds for its survival. By The Long Utopia the climactic changes caused by the eruption have caused large portions of the planet to be effectively abandoned, including most of the United States; the waves of migration caused by this have resulted in new types of communities arising in the Low Earths.