The Democrats were completely out of the game during the civil rights movement. You may not know that the Republican Party pushed for civil rights at a time when they were the minority in both houses of Congress. The Republican Party pushed for civil rights in 1957 to support the school desegregation laws. President Eisenhower pushed Congress for a civil rights voting bill. With complete Republican support but Democratic control of both houses, Eisenhower got a watered down useless bill.
When voting rights came up again in 1964 and 1965, the Democratic majority could not pass a bill without strong support from the Republican party. The same was true for equal pay for women in 1963, a decades old Republican Party platform.
It is the complete absence from the civil rights movement of Democrats that is the reason for their guilt and their perpetual screams of racism.
The major Democratic newspapers in the United States have played on this racist Democratic guilt for a quarter of a century. In 1987 a black woman made completely false rape accusations against six white men, including policemen. The New York Times and Washington Post and all the media carried the Tawana Brawley story for a year. The false accusations were never retracted by the media after the case was dismissed.
The same pattern occurred year after year as the Democrats tried to turn racism into a permanent American issue. The same false charges recurred again in 2006 against the Duke lacrosse team. This helped Obama defeat Hillary Clinton.
This endless Democratic pattern of false racism charges became an issue in 2012 as the president joined in attacking a half white male in Florida in the case known as Treyvon Martin.
The black community has persistently voted Democrat since the early 1960s. Northern blacks always previously voted Republican. The reason for the change is straightforward. Blacks had always voted Democrat in the South since that was the only party. When 6 million blacks migrated North in mid-century they kept their Democratic voting behavior and overwhelmed the Republican blacks in big cities. Blacks remained Democrats because they had moved to cities with only Democratic party opportunities, just like the Jim Crow South. The few Republican blacks moved to the suburbs.