A Short History of the Republican Party

As I  recall it, the Republican party grew out of the Whig party (whatever that was) as a party opposed to slavery. This led to the Civil War, won by anti-slavery forces. After the war, reconstructing the nation began well but ended with Rutherford B. Hayes, who traded away the civil rights of men of color in exchange for the Presidency.  Jim Crow began and lasted for nearly 100 years.

During the Great Depression the Democratic party won the loyalty of a majority of voters by trying to help them.  The Democrats included both America's main progressive elements and the most racist voters. About 60 years ago, the Republicans realized that one way to return to power would be to hint that they were now the genuine home of racists. That would split off some of the Democrats' voters.
  So the Republicans began to hint that they might support a little more racism. This was the dog whistle tactic used by Nixon and Reagan. Soon Southern racists began to shift their loyalties. With more racists voting in Republican primaries, candidates began to compete, seeking racist votes more openly. The most obviously racist candidates began to win primaries. 

To stand out among so many racists, some Republican leaders  began to add that women were forgetting their place, which was pregnant, barefoot and in kitchens. Abortions should not be tolerated by men. Now armed with two issues, white supremacy and male supremacy, the Republicans began to attract fringe elements like the KKK.  Soon the KKK and Nazis were voting in Republican primaries. Instead of nominating Wilkie, Dewey or Eisenhower, the Republicans were nominating Nixon (paranoid), Reagan (senile) and Trump (nuts). Each election the Republicans slid deeper into a concentration of America's worst muck, until, today, the old-style Republicans are leaving the degenerating party in disgust. (This summary omits the Wall Street factors and attempts to repeal social security, Medicare, Obamacare, etc.)