The scheduled and recent primaries in South Carolina and elsewhere remind me that a couple of years ago David Park and I made a series of graphs that revealed some interesting ways in which Democrats and Republicans differed in different states.
We estimated the political ideology of voters in each state using the 2000 Annenberg survey (which asked enough questions for us to separately estimate ideology on economic and social issues, and also had a large sample--good for getting state-by-state estimates).
Here's a graph of the 50 states (actually, I think Alaska and Hawaii are missing), showing the average economic and social ideology of adults within each state. Each of these is scaled so that negative numbers are liberal and positive are conservative; thus, people in Massachusetts are the most liberal on economic issues and people in Idaho are the most conservative:
West Virginians are on the liberal side economically but are extremely socially conservative, whereas Vermont is about the same as West Virginian on the economic dimension but is the most socially liberal of all the states. Coloradans are economically conservative (on average) but socially moderate (or, perhaps, socially divided; these are averages only). (The error bars in the graph indicate uncertainty in estimation; we can't rank the states perfectly, but we can get a pretty good picture of what's going on.)
Democrats and Republicans separately
The next step is to break these voters down into Democrats and Republicans (based on self-reported party identification and following the usual practice among political scientists of throwing the "leaners" into the regular party categories). In the graph below, each state is shown twice: the avg social and economic ideologies of Democrats in the state are shown in blue, the avgs for Republicans in red.
We made these graphs during the 2008 primary election season, and one thing we noticed was that South Carolina ("SC") is in the middle of the pack among Democrats and among Republicans, but it's one of the most conservative states overall. My take on this: South Carolina is a strongly Republican state, and the moderates in South Carolina are likely to identify as Republican. This pulls the Republican average to the left (as they includes the moderates) and also pulls the Democratic average to the left (as they are not including so many moderates).
But the big thing we see from the graph immediately above is that Democrats are much more liberal than Republicans on the economic dimension: Democrats in the most conservative states are still much more liberal than Republicans in even the most liberal states. On social issues there is more overlap (although in any given state, the average Republican is more conservative than the average Democrat).
P.S. How do these rankings fit with our usual rankings of states? Here's a plot showing average economic and social ideology for each state, plotted vs. George W. Bush's vote share in 2000:
P.P.S. More info here.