When war broke out Roosevelt increased spending on defence.
Congress allows countries to purchase goods such as weapons on a cash and carry basis.
Congress allowed the 'lend lease' programme which meant that the USA was supplying vast amounts of war materials to Britain.
Between 1939 and 1941 the US economy seemed to be recovering because of the stimulus of war materials being ordered.
By 1942 unemployment was at 0 and women joined the labour force.
By 1945 12 million men were in the armed forces.
Between 1938 and 1944 America's gross national product doubled.
Industries expanded enourmously because of the war.
This meant taking on laid off worked from northern industrial workers and encouraged the migration of 1.6 million people from the southern states.