The US entered the war in what year?

The United States of America joined in the World War II after 7th of December, 1941; the day on which it's Pearl Harbor was attacked. Prior to this America had stayed away from the war and wasn't a part of either the Allied or the Axis powers. However, when Japan destroyed almost the entire American navy with a surprise bombing of Pearl Harbor which was of its primary naval bases, the U.S joined in fighting along side France and Britain.