Divided Government and the Passage of Partisan Legislation, 1947-1990

Recent literature has provided some evidence that the presence of divided government does not affect the amount of significant legislation passed by Congress and enacted into law (Mayhew 1991). In this article, I argue that although there may not be a difference in the absolute number of bills passed during unified and divided periods, there nevertheless may be an important difference in the formation of coalitions during divided and unified periods. Specifically, I argue that party unity votes that favor the dominant party are more likely to form on final votes of passage during periods of unified government. I use regression analysis and probit analysis to determine if there is empirical support for this hypothesized difference in coalition formation. I find that the presence of unified government significantly increases the likelihood that a bill will pass through Congress with a party unity vote favoring the dominant party. The estimates are statistically significant for both the House and the Senate.