America is at an interesting historical juncture. An African American may well be elected president in a few weeks. From the 1600s to 1865 black slavery in this country was sanctioned by law. From the end of Reconstruction until 1965, a significant proportion of blacks in the South could not vote. Passage of the Civil Rights Act of 1964 and the Voting Rights Act of 1965 - acts signed by a Democratic president, supported in Congress by most Republicans and most northern Democrats and strongly resisted by most southern Democrats - led soon thereafter to a historic shift in party allegiance, in which the "party of Lincoln" adopted the so-called "southern strategy" of appealing to the racism of white southern Democrats, thereby driving blacks into the national Democratic Party. (It's worth noting that an average of only 51% of blacks nationally in 1952, 1956, and 1960 identified themselves as Democrats.)
It remained for a young campaign worker in Richard Nixon's 1968 campaign, Kevin Phillips, to write a book the following year, The Emerging Republican Majority, called by Newsweek "the political bible of the Nixon era," in which Phillips argued, "the GOP can build a winning coalition without Negro votes. Indeed, Negro-Democratic mutual identification was a major source of Democratic loss [in 1968]." The southern strategy continued to be openly employed in Republican presidential campaigns as late as 1988, and more subtely in succeeding elections.