Shifts in American political geography (“realignments”), which I wrote about on Thursday, can be viewed at a glance using the following diagram. It allows us to see just how little change there has been in recent years – including 2016 so far. In this diagram, the closer two points are, the more correlated the national pattern of state-to-state voting. Distance between points approximately represents “unshared variance” between two elections, which is defined as 1 minus the correlation coefficient squared. The reason that unshared variance can be plotted visually is that mathematically, it acts like distance: changes in successive elections can gradually add up, eventually altering the political landscape. Which appears to be what is meant by a “realignment.” Roughly speaking, left-to-right measures the Civil-Rights-Act-triggered realignment, so that’s the South going Republican plus maybe Northern states trending Democratic. Up-to-down reflects the second realignment.

(Math note: To make this plot I used multidimensional scaling, in which I plotted three of the elections to get the graph started, then added more elections one at a time, re-optimizing the graph each time. My collaborators and I have used this approach before to analyze how brain architecture has changed over the course of evolution. The scripts and data are here. Okay, back to the politics.)

Changes in partisan alignment do not coincide with transitions in power. 1976 to 1980 (Carter to Reagan), 1988 to 1992 (Bush I to Clinton I), and 2004 to 2008 (Bush II to Obama) were all momentous transitions, but in no case did the political map rearrange itself. On the other hand, 1960 to 1964 (Johnson’s re-election) showed a massive upheaval in which Democrats lost their previously strong grip on the South. As I wrote the other day, this change took three more elections to play out, culminating in 1972, the year of Nixon’s re-election and his famous use of the Southern strategy. I would therefore call 1960 to 1972 the culmination of a first great modern realignment of the parties.

This map shows a perhaps equally great second shift, starting in 1976 and indicated by the red path. Each step was small, but over time it added up. Comparison of the 1976 and 2012 electoral maps (see below) shows that during this time, two things happened: (a) the South became securely Republican (think of Gore losing Tennessee in 2000), and (b) Democrats captured Western states starting with Washington, Oregon, and California, and eventually including Nevada, New Mexico, and Colorado. These changes may be partly racial, partly economic/cultural.

Note that the distinction between “Phase 1” and “Phase 2” is somewhat artificial. Really, the major event separating the two phases was the Watergate scandal and Nixon’s consequent resignation, which caused massive damage to Republicans and led to the election of Jimmy Carter, a previously obscure Southern governor. If we leave out 1976 and 1980 from the graph above, the remaining elections look like this:

In this representation, the shift of 1984-2012 corresponds to (b) above, the loss of Western states by Republicans. Washington/Oregon/California/Nevada currently add up to 80 electoral votes, marking a substantial shift toward Democrats. Racial diversity is an obvious driving factor here, with some additional role for new-economy jobs growth.

Perhaps a broader lesson from this diagram is that much of the last 50 years has involved continual change in the configuration of the electoral map. The exception is 2000 to 2012, a static period during which polarization has been massive (multiple Republican takeovers of the House of Representatives, impeachment of President Clinton, multiple government shutdowns, partisan passage of Obamacare, decreased productivity of Congress). Against this backdrop, any change may seem like a lot.

As I wrote last week, despite the upheaval on the Republican side there might not be much change to the map. The change from 2012 to 2016 currently looks, at most, like one-tenth the size of a real realignment.

The graph makes it look like 2016’s partisan alignment might be moving back a little bit toward 1964. I would not read too much into that. I think it is probably noise. Most states are unpolled, and this could just as well be caused by not having enough data. From a numbers standpoint, so far it looks like Donald Trump is basically Bush/McCain/Romney minus Utah, which is amazing considering that all three of those people have rejected Trump in various ways.