Two points:
- This is a measurement from political "bottom" to bottom (to use a stock chart metaphor), from the depths of McCarthyite Cold War anticommunist hysteria, Korean War, etc to our own present, but very different, depths. What it mainly measures is the bolt of the racist redneck yahoo vote from the Dems. BUUTT...
- By 1972 this bolt was all but complete on the national level at least. So if the Dem _vote_ (not to be confused with the Dem party apparatus) has moved rightward since then, it has done so without the redneck vote. That means the more metropolitan middle class and working class Dem voters have also "moved right" since 1972.
It may be the case that the metropolitan Dem vote has "spontaneously" moved right, but I'd submit that it is more likely that the Dem party apparatus, in an ongoing effort to hold on to their remnant redneck vote (not all the racists abandoned the Dems, and certainly not all at once!) especially in Old South locales where their candidates still split votes with the Republican Presidential ticket, dragged their metropolitan vote "rightward", rather than "follow" these voters. Clinton the Black Man Executioner was the epitomy of this "triangulation" process. They were vastly assisted in this process by the change in the world situation after 1989. IOW, the party apparachiks were and are are well to the right of their metropolitan vote, I suspect. To give up this appeal to the rednecks would be to condemn themselves to minority status for eternity under the present political institutional arrangements, highly biased as they are against the metropoles.
But we'll never really know so long as we don't have an independent progressive political party, at least.
But 1972 is the more relevent point of reference, not only per above but because 1972, and not 1952, mark the beginning of _our_ contemporary era. Hell I wasn't even born in 1952...
-Brad Mayer