The Civil Rights era does not begin with the Brown v. Board of Education decision, or with Martin Luther King, Jr., or Rosa Parks, as important as they were. It's roots really lay in World War II. The Roosevelt administration faced great pressure to allow African-Americans to gain employment within companies that were getting huge federal contracts, and to some extent they complied. They also had to engage in anti-racist propaganda to combat the Nazis racial theories and drum up support for the war effort. Even more important, about one million African-Americans and tens of thousands of other minorities gained valuable experience being trained by the military and in serving overseas during the war. This gave them quite the reserve of courage to battle racism when they returned home to the United States.
The following anecdote regarding James Brazier's death from 1958, taken from the SPLC website indicates the dominant mindset of many whites in the U.S., not just the southern states, prior and during the Civil Rights era.
Brazier was beaten to death in front of his wife and children by two police officers. County Sheriff Z.T. Matthews was later quoted in the Washington Post saying, "There's nothing like fear to keep niggers in line."
Politically, though violence was most often disdained, keeping blacks in line was supported almost across the board in the South. In March 1956 US Senator Sam Ervin of North Carolina had drawn up the "Southern Manifesto" which promised to fight to keep Jim Crow alive by all legal means. Ervin managed to gather the support of 101 out of 128 federal legislators from the eleven states that had been part of the Confederacy.
Shortly afterward though, a revolution had taken place. "Fear" was no longer an adequate force to keep African-Americans from challenging Jim Crow and segregation laws across the country. Not just in courts of law, but out in the open at lunchroom counters, on buses, at the polling place, and in all other areas of the public sphere, even though they knew their lives were on the line, they kept up their protests in the face of horrifying violence and changed the face of race relations in this country. Cesar Chavez, the American Indian Movement and other advocacy groups also had their initial successes during this period. While racism did not disappear, this is the period where people went from publicly advocating racist attitudes, to having to couch them in metaphorical or coded language. And, the advocacy of outright violence against a person because of their color became taboo in theory, if not yet completely in practice. In many ways, the promise of the Reconstruction era's de jure accomplishments toward racial equality, finally became manifest on a de facto level.