Okay, so the blacklash from white Americans to civil rights movements was occasionally very ugly. Why do you think that was?
People in general get very attached to their ways of life. They think that the way things are is the way things are supposed to be. Because of this, they can get very defensive when their way of life is (they feel) being attacked.
I believe that this is why there was a sometimes ugly backlash against the Civil Rights Movement. Whites in the South felt that segregation was the way things should be and that their society would fall apart if it were banned.
Whites in the North did not want black people living near them, for example. They felt that threatened their way of life. That's why Martin Luther King Jr. was hit in the head with a brick while leading a march in the Chicago area.
Most, but not all, of this backlash occurred in the South, where segregation and discrimination against blacks was most common. Southerners not only widely held racist ideas, and had for a long time by that point, but were very defensive as a whole to being told how to live their lives by a "Yankee" government up north. This defensiveness dates way back to the 1830s, before even the Civil War. For generations they had been told the North were meddling in "the natural order" of things. Whites in the South also felt betrayed by the Democratic Party, which had defended segregation and racism for decades and then with Truman and Kennedy, had switched.