How has America seen a pattern of oppression over the years?

Through out American history we have seen waves of oppression spread nationwide. There are many example of how in certain times the minorities were given more rights and before they knew it those freedoms were snatched away just as fast as they received them. During the civil war, African Americans fought for their freedom and had the chance to be involved in the war. After the war ended African Americans still were enslaved by societies inability to concede emancipation. This is only one example more examples are

•  During WWI African Americans were sent to war and got more job opportunities state side along with women while the healthy white men were away. After WWI African Americans went back to having lower jobs and being oppressed and women went back to the kitchen. 
• During WWII the cycle repeated itself but after the war ended African Americans and Women weren't going to allow oppression any longer, and stood up to the masses

I believe America is still continuing this cycle with the treatment of muslims, after 9/11 our nation grew paranoid about more attacks on American soil, so the masses allowed for the government to pass legislation that allowed American citizens to have their rights infringed upon just to  allow certain groups of people peace of mind. As Martin Luther King Jr. said "Injustice anywhere is a threat to justice everywhere"