As World War II was ending, the Cold War began. This was to be a long lasting and continuing confrontation between the Soviet Union and the United States, lasting from 1945 to 1989. It was called the Cold War because neither the Soviet Union nor the United States officially declared war on each other.
They created the Jim Crow Laws, which made African Americans unable to do certain things such as vote and hold office, and the Ku Klux Klan (KKK) threatened African Americans in many ways, even going as far as to murder them.