Europe is, and was, a major ally of the US, and they are, and were, both large trading and business partners. Their economies also intertwine with each other, and base off each other heavily. The rebuilding of Europe was important to the US for these reasons, and possibly because they felt they had a duty to help for they had been fighting in Europe as well.
Rebuilding much of Europe and starting the United Nations.
The US Secretary of State, George Marshall was the author of the Marshall Plan for rebuilding Europe after WW II.
The US faced the difficult task of helping to rebuild Europe and Japan. The US also faced a difficult task in rebuilding war-torn Europe.
The Marshall Plan was a US Foreign Policy designed to promote CAPITALIST DEMOCRACIES in Europe by rebuilding postwar Europe and making Europeans more moderate in their approach.
The rebuilding of the US after the Civil War was called the "Reconstruction Period".
WW I was fought in Europe, and it was enormously destructive. Homes, factories, and other structures and infrastructure were massively damaged or destroyed. In the US, there was no fighting. American soldiers had to travel to Europe to participate in the fighting. So the US was physically intact after the war (despite casualties, of course) and therefore was better able to develop its economy, while Europe was rebuilding.
The United States wanted to spread democracy and capitalism while the Union of Soviet Socialist Republics wanted to spread communism and socialism.
Quite gently. US helped with rebuilding, etc.
Reconstruction
It was VERY important
It was VERY important
It was VERY important