What actually cause them to join the war was the attack on Pearl Harbor
The proximate cause was Japan's attack on Pearl Harbor (December 1941). Following that, the US declared war on Japan and, in response, Germany and Italy declared war on the US.
After World War 2, the US had the strongest economy in the world.
US PresidentHarry Truman was US President at the end of World War 2.
The 8th of December 1941 was the date that the US joined world war 2
405,400 US casualties are recorded for World War 2
1,700 US Civilians were killed during World War 2.
2 in/volved
World War 2
World War 1: The UK, and Japan. World War 2: The UK, and Russia.
Germany
japan
No Germany declares war on US