Answer:
American economy wasn't destroyed during WW1 as it was the economy of other strong countries - mostly European. Those countries were practically destroyed and their economy was destroyed. On the other side United States preserved its economy and even was giving a large amount of money during and after the war as a loan.
Step-by-step explanation:
United States entered the war in 1917, and the war wasn't lead on their territory, which means there was no destruction of any kind. They stabilized their industrial production and even increased it, especially military, which enabled them to became the world strongest power after WW1. Also, they were the main creditor of all the countries that were affected by the war, and thus helped them recover after the war.