In the past few decades, have Americans moved right? Berkeley political scientist Paul Pierson has written that the Republican Party has moved sharply right in the last three decades and has been very successful in spite of the fact that the American public has not moved right at all during the same period. (He argues that they have been so successful because they are more cunning and unified than Democrats, and their going against the public's will has undermined democracy). But is this core claim of his true that Americans have not shifted? Since 1974 the GSS has asked respondents to describe themselves on a range between extremely liberal and extremely conservative. I calculated the mean score for all the years available from 1974 to 2004. Here are the numbers for each decade (4=moderate and higher numbers are more conservative):

1974: 3.98
1984: 4.17
1994: 4.17
2004: 4.23

And the trend is stronger when we only look at the people who actually vote:

1974: 3.97
1984: 4.22
1994: 4.19
2004: 4.34

So Pierson is wrong, they have gotten more conservative. On the one hand, the move to the right has only been 1/3 of a standard deviation, but in politics even small shifts can swing elections.