President Roosevelt's New Deal was designed to improve conditions for people who were suffering in the Great Depression. It gave so many people hope because it promised new jobs and to pull people out of their horrid living conditions.
In a state system, the President of the Senate is generally the lieutenant governor.
The founding of the United Nations
The Cold War
The origins of the Civil Rights movement and desegregation
The initial economic burden (war made for a lot of jobs and opportunities that ended when war did- but eventually it lead to an economic growth and gave us the capitalism we have today.
There are many effects the war had that range across many different areas of study.
Cultural, political, economic- hope these few examples help you.
I remember I learned this in 6th or 5th grade so what happened in the 9/11 is that there were 2 tall buildings and a plane crashed both of them and they probably did it in purpose and a lot of people died that day