When did the US get involved in World War 2?

Answer 1

The US was "unofficially" in a great many ways "involved" in WWII from the very start -- September 1, 1939. The US became an official combatant in what was later called "World War II" on December 8, 1941, the day after the Japanese bombed Pearl Harbor.

The US was officially neutral from the begining of the war, but many Americans supported the Allied cause while very few Americans were sympathetic to the Axis. In March 1941 the United States offered aid to the Allies in the form of the Lend Lease program by which the Allies were given war materials in exchange for the US being allowed to use Allied bases. This made them an Economic Ally while still a noncombattant. In addition American warships and aircraft were used to escort Merchant convoys and protect them against U-boat attacks.

This changed when the Japanese attacked Pearl Harbour on December 7, 1941 and the United States became fully involved in the war.

Answer 2

After Pearl Harbour Day, Dec. 6th 1941. The war had been going on since 1939, but the US called it "the European War" until they declared war on Japan and her allies.