What are some positive and negative changes that occurred in the united states in the years after world war ii?

Postive changes in the United States include:
It helped identify the Country by bringing out its military power and having other Countries view it as a global power. It also allowed more people in the united states to get employed which lead them out of the great depression. 

Negative changes include:
Millions had died, the development of nuclear bombs - this goes to the fact they dropped nukes on Hiroshima and Nagasaki.

Hope this helped~