The unwritten constitution of the United States includes the Aristotelian and Gödelian Constitutions, the various constitutions in and outside of the courts, and the features of distinctive constitutional regimes. This chapter details these unwritten constitutions and highlights the empirical dimensions of constitutionalism in general and of American constitutionalism in particular, emphasizing how the empirical and normative dimensions of constitutionalism cannot be separated. Constitutionalism is an intricate blend of law and politics, not a means of separating law from politics. Written and unwritten constitutional politics intertwine with written and unwritten constitutional law in ways ignored by both legal and political science versions of the law/politics distinction. This chapter also explores some dynamics in contemporary constitutional politics in the United States and shows that changes in unwritten constitutional politics have not yet been captured by written or unwritten constitutional law. Bringing the structure of constitutional politics back into the structure of constitutionalism promises better constitutional analysis and, perhaps, better constitutional practice.