"I rather disagree. In fact, I think American involvement was the major factor in Germany's defeat -- and I'm not just saying that because I am an American.
Consider that long before Pearl Harbor, America was in many respects already at war in Europe. Supplies, armaments, pilots (such as the Eagle Squadron), materials, ships (the Lend-Lease Act), etc. were pouring into Britain. I dare say that without those supplies, Britain would have been overrun or forced to capitulate before America was officially part fo the war. Either way, that in turn would have allowed Germany to concentrate on Russia, rather than the two-front war she was forced to wage, quite possibly leading to her victory over all of Europe."
Consider what you are saying here. The actual war (european theater) was basically a huge struggle between the Soviet Union and Germany, with Britain harrasing Germany with air raids and such in the west. One of the mistakes Hitler made was thinking he could easily conquer the Soviet Union (no nation, not the U.S. or anyone could have done so because of the sheer size of the country). The best he could hope for was to take the oil fields and Moscow and force a treaty with the Russians. Even so, the Russians would still have been in an excellent position to rebuild their industry in the far east and prepare to retake the lost territory. The U.S. came into the war tipping the balance, by opening the second front. That's what Nep Parth meant. The U.S. was not the deciding power though, Russia was(had there been only one front in the west, the U.S. couldn't have liberated europe quite so easily). The U.S. did tip the balance between the Soviet Union and Germany however.
"No country in the world could even approach U.S. industrial might..."
Well, people often underestimate wartime Russia's industry during WWII. Believe it or not, but the Russians actually produced more aircraft than the U.S., and much better tanks than any allied power too.
But enough about the WWII issue. Let's get back on topic.
