The story was heavily influenced by the events of World War I, and reflects U.S. sentiments at the time of writing. When the war broke out, Americans were predominantly isolationist and wary of being drawn into a European war. Burroughs imagines a future two centuries onward in which that view prevailed and the western hemisphere severed contact with the rest of the world. Consequently, the eastern hemisphere has exhausted itself in war and Europe has descended into barbarism while the Americas, sheltered from the destruction, have continued to advance and joined peacefully into the union of Pan-America.(Wikipedia)