What are the methods the federal government used to discriminate against black americans?

Segregation of society, meaning black and white schools, hospitals ,etc.

the answer is

so they can differentiate themselves from others as they saw themselves as the superior race. the star was basically a symbol that meant you are a less of a person than i am because of my race. the star was also degrading for those who had to wear it because they were aware of this and the nazis used the notion to make them feel less like a person.