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Over the past decade, legislative research has directed our attention to new ways
of understanding and characterizing the structure and stability of legislative voting
coalitions. Most accounts of the U.S. Congress, for example, contend that legislative
voting is best described by a unidimensional structure breaking down along a left-right
ideological continuum and with strong durability in this structure for most of history
(Poole and Rosenthal 1997). What we do not know is whether the patterns found
throughout the history of Congress, such as the unidimensional structure of conflict or the
recent polarization of the parties, is peculiar to the US Congress, or whether these
patterns are part of broad and far-reaching changes in the political context of the country
and thereby encompass the state legislatures as well. This raises a pair of questions that
inform this analysis. First, to what extent do state legislatures reflect the U.S. Congress?
When we learn things about Congress, are these descriptive generalizations applicable to
the states as well? Second, how well does the rich body of developing legislative theory
that is largely congressionally-based apply to the states? To what extent do congressional
theories addressing the impact of rules or other institutional features, of the effects of
money and interest groups, or actions of voters or other aspects of the external
environment hold for the state legislatures?
We know, of course, that the state legislatures differ from Congress in numerous
ways, but it is nevertheless useful to entertain the expectation that theories making sense
of the patterns of congressional politics will also be useful for understanding the states. In
this paper we are interested in whether the patterns of roll call voting in Congress, and the
impact of parties on these patterns, are reflected in the state legislatures. Drawing on
recent work on Congress we attempt to determine the extent to which legislative politics
Convention