Why did American society change so dramatically after World War 1?

Because after ww1 they became international manufactures of of a huge variety of goods, and were able to compete more easily then the Europeans as they had not suffered thesame damage durin the first war. after ww2 they made a fortune out of the sale of weapons and equipment to the rest of their ally's all this wealth is bound to have an effect. It made many Americans question slavery.