History of racial segregation in the United States
Segregation kept African-Americans from having the basic rights that the Founding Fathers had written into the Constitution of the United States.  Law-makers, government officials, voting officials, and police officers were all white.  This prevented African-Americans from having any say in their government; being able to get the same voting rights as white people; having police officers protect them; or being able to get justice for crimes against them.  Because they could not count on all-white police forces to protect them, violence against African-Americans, especially lynchings, increased.  Because African-Americans could not vote, they also could not serve on juries.  This meant that if a black person was ever on trial for a crime, the jury would be all-white.