The 1940's was a very important decade for America. One of the biggest events was world war 2, even though it was not in America they did help a lot. As of 1940 the American president was Franklin Delano Roosevelt, he was commonly know by his initials FDR and he was the 32nd president of america. He was elected for a fourth term (1933-45) the longest running president in history, the most popular president of America to date.