Why did the united states shift away from the policy of isolationism after world war 2?

How did slavery end in the united statesa. it ended with the emancipation proclamationb. it ended when the union won the civil warc. it ended with the fifteenth amendmentd. it ended with the 13th amendment

Why is the end of the cold war tied to the american domestic economy during this time?

Who was the first present of the united states