@Sep@ClocktowerEchos But Caesar was one of the few literate members of the Legion, and it was only by chance he found a copy of the Comentarii de Bello Gallico, and he took great strides to prevent anyone else from knowing that their civilization had been based (rather inaccurately) on Rome. The specific tribal identities in America are very likely to be the twisted results of a culture originally designed by someone with a knowledge of history, but a history of which modern day tribals have no appreciation of. The NCR, too, was created by residents of Vault 15, and it was through them that democratic ideas survived, not through the active enfranchisement of citizens.
Aside from the Enclave, people seem to live extremely sedentary, subsistent lives, with little need or facility to care about any form of national identity, and those more civilised factions with some understanding of the past are the ones who tend to actively oppose the trappings that lead to war - abuse of technology(Brotherhood of Steel), nationalism (Caesar's Legion), and so on.
I'm sure some vague sense of Highlander isolationist attitude survived the Atomic bomb blast, but I wonder would they still identify southerners as "the English", or would anyone in England care in the slightest?