In 1870, at the time of German national unification, the population of the United States and Germany was roughly equal and the total output of America, despite its enormous abundance of land and resources, was only one-third larger than that of Germany. Just before the outbreak of World War I the American economy had expanded to roughly twice the size of that of Imperial Germany. By 1943, before the aerial bombardment had hit top gear, total American output was almost four times that of the Third Reich.
