We do not know who you mean by saying America. America is several countries, some of which were neutral during WWI. Nor do you state who you are. It is therefore impossible to answer your question.
They were allies
Americas allies did most of the fighting, do your research and stop asking broad questions
They were allies against the Germans.
They were allies and fought for each other on the European theatre
Sometimes the Allies in World War 2 are referred to as co-combattants, given the uneasy relationship between the Soviet Union on the one hand and Britain and the US on the other other.
The Triple Entente which consisted of Britain, France & Russia
Great Britain, France, Soviet Union.
Norway's allies were Britain, and the allies including the U.S.
they were allies in world war 2
The Netherlands were Allies in World War II.
The Allies
America helped it's allies during World War 2 by shooting people and stuff. they were smart.