What probably would have happened differently if Hitler didn't declare war on the USA?

Question:

why he did this? (As many think this was a really stupid mistake due to the problems Roosevelt was having getting the American public to support a war with Germany...here they say Hitler helped America join the war against Germany by at least 2 years.since it would take that long to talk congress, etc into mobilizing for war against Germany)

Answer:

It is doubtful that America would have voluntarily entered the war with Germany, although Truman had been trying to get Congress to respond to American casualties in the Atlantic. However, the general mood may well have been that America had it's own war to worry about after Pearl Harbour and, while continueing with lend lease, may have balked at borrowing trouble from Europe, which many see as localised tribal warfare.

So assuming that America stayed out, it is likely that Russia would have defeated Hitler. This may have taken slightly longer, since Britain may not have been able to launch a second front onto the continent and may have gone via Italy. This means that Russia would have conquered all of Europe.

It is doubtful that America would have entered a conflic with Russia following this. Although American troops would have had recent experience against the Japanese, fighting the Russians is another matter.

Russian tank development was significantly greater than the Americans. The Sherman, although making sence economically and logistically, was a piece of junk when comparered to the T34/85. Trying to go toe to toe with an IS II or IS III would have been embaressing, since these vehicles were comparable to the heavy German equipment. In fact, the IS III was probably better than the Konigstiger.

During the Normandy Landings, the allies enjoyed air superiority. America fighting against Russia would face a determined and skilled enemy with viable air cover. In short, America may have found itself outclassed and outgunned if it tried to attack Russian territories in Europe.

Should America wish to liberate the West from Russian dictatorship, given it's 1940s/50s load out of armour and planes, the use of Nuclea weopons in order to secure teritory and eliminate Russian arms seems very likely.

So overall, America probably would have polished off the Japs and stayed home, leaving Europe to the Russians.

Luck