This document provides background information on the political and economic isolationism policies of the United States in the 1920s-1930s and the events leading up to its entry into World War II in 1941. It discusses the Neutrality Acts of the 1930s, FDR's 1937 quarantine speech, and the Cash and Carry policy of 1939 which allowed allies to purchase arms. It also covers increased defense spending in 1940, the Lend-Lease plan to aid allies in 1941, and the Pearl Harbor attack which led to the US declaring war on the Allied side against the Axis powers.