In the 19 hundreds, blacks were segregated against greatly by white people. This happened on many different occasions and in many different ways.
One way was a group called the KKK who were a white supremacist group devoted to killing and torturing black people.
There were even separate restrooms, water fountains, stores, and restaurants meant for either only black people or only white people.
Segregation did not only push those limits. Black people were also given worse quality schools and educations.
The schools were either black only or white only. There were much more white schools than blacks and normally the black schools would end up being smaller than the white schools.
Since black people were denied jobs sometimes, the teachers at black schools were not very advanced. This led to their students not being very advanced while whites had education that was just fine.
Do you have any questions?
We hope you realize how big of a problem this was. You can help the problem by treating everyone well no matter their race, and always remember that everyone is equal and they hold their own qualities within themselves.