How did World War I and World War II help the United States economically and with regard to its role in the in?

Both wars contributed to the growth of the US Military Industrial Complex.

Look it up, and do your paper on that. You'll get an A. You'll impress your teacher and scare yourself in the process.

Former President Harry Truman mentions it in his farewell speech as he leaves office. And he regarded it as the 'single greatest threat to the security of a free and democratic society'.

You will see why the government votes for things they don't need, and why foreign policy is the way it is.

I agree. The US industry setup for total war, meaning all industries worked full force to provide for the war. The Depression ended as more people got jobs from WWII factories.