ABSTRACT
"All politics are local," said Tip O'Neill, Speaker of the House from 1977 to 1987. If only because the Congress of the United States must amalgamate the diverse preferences of constituencies, the task of finding a simple structure to explain how members of Congress vote when the roll is called might well be hopeless one. In this chapter, the authors develop a parsimonious model that accounts for the vast majority of millions of individual roll call decisions during the 217 years of roll call voting in the House of Representatives and the Senate. The fact that most roll calls are splits implies that one can represent most votes as mappings from the issues onto the continuum — examples would be the level of the minimum wage; the extent to which assault weapons should be banned; and whether prayer, silent or vocal, should be permitted in schools. The chapter also presents an overview of the key concepts discussed in this book.
