The partisan divide has increased because the Republicans have become much more conservative (and the Democrats more liberal) than they were between 1933 and Reagan's victory over Jimmy Carter in 1980.He continues on to present a general overview of how the Presidents of the last fifty years illustrate this shifting.
People will scoff at the idea that the GOP post-1980 is much more conservative than before 1980, but the facts prove my case.
Fortunately, there exists an empirical method for examining this assertion. The GSS asks respondents about both their political orientations and their partisan affiliations. The following graph shows the mean political index values of white Democrats and Republicans by year. Positive values indicate conservatism and negative values indicate liberalism, with zero representing exact political moderation. One standard deviation is 1.35 index points.
Indeed, the political gap between Democrats and Republicans has trebled to become a chasm over the last few decades.
My working narrative is largely confirmed by this. With Reagan's asendancy, conservative Democrats began drifting away from the Democratic party and liberal Republicans backed away from the increasing social conservatism of the Republican party. After Reagan and the effective end of communism, the blue-blooded George HW Bush came to signify a more centrist GOP resembling what had existed before Ronnie (with the Iran-contra affair, for which Reagan's popularity suffered, playing a role in tarnishing the conservative label). In a few years, that had faltered and conservatism again came to define GOP voters with the 'Republican Revolution' of 1994. We continue on this political trajectory today.
GSS variables used: PARTYID(0-2)(5-6), POLVIEWS, YEAR, RACE(1)