Liberals and minorities remain generally Democratic. The western progressives and machine politicians have gradually died off I think. I knew the South switched its loyalty during the sea-change in Federal race policy during the 1950s and 60s. That was pretty easy to see. In the 1970s many young men and women who would naturally have become Democrats became independent voters in reaction to the war in Vietnam.
I couldn't recall what caused the working-class whites -- many of them union members -- to join the Republican ranks.
In Washington Post column today, Dionne dates the disaffection of blue collar white men with the publication of the Kerner Commission report, which blamed white racism for riots in black ghettos. In this article, When Liberalism's Moment Ended, he says:
A shrewd politician named Richard Nixon sensed the direction of the political winds. When President Johnson's commission on urban unrest released its report in early 1968 and blamed the previous year's rioting on "white racism," Nixon would have none of it. The commission, he said, "blames everybody for the riots except the perpetrators of the riots." He urged "retaliation." . . . It is easy to forget that the core themes of contemporary conservatism were born in response to the events of 1968. The attacks on "big government," the defense of states' rights, and the scorn for "liberal judicial activism," "liberal do-gooders," "liberal elitists," "liberal guilt" and "liberal permissiveness" were rooted in the reaction that gathered force as liberal optimism receded.