To say that it took the American's awhile to become invested and involved in WWII would be a gross under statement. The first step that the American's took was the attempt of a conference in Bermuda wondering what to do with the Jews in Europe. There was a lot of debate as to the solution of what would be done, however, nothing came of it in the end (history.com).
With the help of Secretary of the Treasury Henry Morgenthau, Jr, who was Jewish, the government was able to write a report that was then presented to FDR. On January 22, 1944, "the president issued Executive Order 9417, creating the War Refugee Board (WRB)" (history.com). Sadly this didn't stop the blocking of war efforts, and there was great concern over the American's doing anything to help. While the efforts did help save the lives of 200,000 Jews, speculation states how many more might have been saved.
It wasn't until December 7, 1941 when Japanese bombers decimated Pearl Harbor, that America became fully engulfed with in World War II. Hitler and Mussolini followed suit declaring war on America. All statements of neutrality were set aside and troops were sent to European shores in droves. Thus, America was officially a part of World War II.
Photo credit: http://varesources.org/va_alert.php?clcsr=1
History.com. (2009). Retrieved from http://www.history.com/topics/world-war-ii/american-response-to-the-holocaust