The South and West in U.S. presidential elections

In the last 20 years there have been 5 presidential elections. In two of these elections, those in 1992 and 1996, Ross Perot was a candidate who did much better than the average third party candidate, so we have had 12 "major" candidates: Clinton-1992, Bush-1992, Perot-1992, Clinton-1996, Dole-1996, Perot-1996, Bush-2000, Gore-2000, Bush-2004, Kerry-2004, Obama-2008 and McCain-2008. If we take the election percentages for each of the 50 states (leaving out the District of Columbia because it is such an outlier that it confuses the results), and run a component analysis on them, the results shows two significant components. Plotting the component scores for the various states, we get this:


The 10 states shown in red are, from the bottom up: MS, TN, AL, SC, LA, AR, GA, NC, VA, and KY.

The 13 state shown in green are, from left to right: UT, ID, WY, NE, AK, OK, KS, ND, SD, MT, IN, AZ, and CO.

The purple state between the two, at about [-.8, -.3], is TX

The first component (the X-axis) generally orders the states from the red republican-leaning states (UT, ID, WY) at one end to the blue democratic leaning states at the other end; the five stats with the highest first component scores are MA, RI, NY, HI, and VT.

The second component separates the southern states from the rest of the states; the five most "unsouthern states" are ME, MT, ID, AK, and VT.

So (roughtly) the lower left quadrent are the southern states, and the upper left are what may be called the "interior west" (with Alaska fitting in with these states).

TX, being a state the borders the south and the west (there is a saying to the effect that the border between the south and the west runs between Dallas and Fort Worth), unsuprisingly lies between the two groups.

What we can notice is that the southern states show up as only moderately republican (taken as the first component), eight of the thirteen "western" states (UT, ID, WY, NE, AK, OK, KS, and ND) are are farther to the left than the leftmost southern state (AL). Additionally, the second component absolutely separates them. Placing Texas in either group, considereing it either a southern or as a western state, does not change this; the two groups would still not overlap in the second component.

While there doesn't seem to be any obvious groupings of the states to the right of the scatter chart, I find it somewhat striking how two groups do separate out so distinctly.