"Or, for that matter, what would a map of Europe look if the US had remained a small nation unable to join the allies in WWI or WWII ?"

Uncle Phil -

While I generally agree with your overview of the events in question, your speculative point about twentieth-century Europe bothers me . . . (and I hate to be a stick in the mud about this) . . . HOWEVER, US involvement in the Great War led to the Treaty of Versailles, which led to the rise of the National Socialists in Germany, and thus to WWII.

WWI also gave us the Bolshevik Revolution in Russia - damn, that "War to End All Wars" was a disastrously stupid war.