Both parties thought the black vote was important since both wanted to win the Presidency, which means that every voter group matters-- even if a particular group of that sub-group might not matter in a less contested state, the overall group matters for winning. As does party control of Congress, since even if your district is completely white, you want your compatriots in districts with large black populations to win, so you can be chairman of a committee, not just ranking minority member. Remember the 1950s was the last decade before the 1990s when both chambers and the Presidency were swinging back and forth between the parties.
This fixation on the powerlessness of poor and minority voters as an argument for the lack of importance of voting and serious political engagement is just perverse. Of course, the deck is stacked but the passage of multiple civil rights laws over the years, including most recently the 1991 Civil Rights Act, which overturned a number of bad Supreme Court decisions on civil rights.
You think it was mass movements that pushed through that bill or the voting power of black, latino and allied groups?
Nathan Newman