Among state political analysts, a common pastime is classifying the states according to their degree of Republican or Democratic partisanship. The most frequently cited is Ranney's (1976) classic measure of interparty competition. The Ranney index is a combination of the two parties’ relative legislative strength and the two-party vote for governor. Used as a directional measure, the Ranney index arrays the states on a continuum from safely Democratic to safely Republican. “Folded,” the index measures the distinction between “competitive” states and “one-party” states. Others, notably David (1972), have developed indexes of state partisanship based on the vote for a wide variety of state offices. The rationale for classifying the states on the basis of partisanship is the measurement of meaningful differences in the two parties’ relative chances of winning elections. Presumably, some states almost always elect Democrats and others almost always elect Republicans, with others in the middle enjoying the presumed ideal condition of “competitive” elections.

To what extent are statewide election outcomes determined by state levels of Democratic versus Republican partisanship? Our measure of state party identification can help to answer this question. In Chapter 6, we saw that the correlation between state party identification and legislative partisanship was a quite high 87. This strong correlation was to be expected, because the measure of legislative partisanship is the net balance of all legislative races, averaged for each chamber over eight election years.