The US finally entered World War I in 1917, when it had bogged down after three years of fighting. The additional manpower turned the tide, and by 1919 Germany had lost most of its territorial gains. The war was ended by the Treaty of Versailles on June 28, 1919.
1941
1917
1917
1914
on decmber 8 1941
1917
1909 to 1944 The US entered World War 2 in December of 1941.
The United States declaration of war is from 6 April 1917.
The US did enter World War 1, though not till 1917.
1917
The United States joined the Second World War in December 1941 as a response to the Japanese attack on Pearl Harbour.
the us decided to enter world war because they want the resources of france, and they want to keep on ruling france.