Despite its substantial theoretical flaws, dual federalism—the model of American federalism according to which the field of federal regulation is separated from the field of state regulation in a mutually exclusive (or close thereto) fashion—continues to attract sophisticated adherents. In this Article, I debunk the myth that the U.S. Supreme Court was ever committed to a dual federalist interpretation of the Commerce Clause from which it subsequently departed. Prior to the Civil War, the Supreme Court expressly embraced overlapping federal and state regulatory authority with respect to interstate commerce. And, even with respect to the Gilded Age between the Civil War and New Deal, the Court’s commitment to dual federalism was only nominal. The Court deployed the same terminology in reviewing federal and state commercial regulations and taxes, but its application of the doctrinal rules and its understanding of the underlying theoretical basis for the rules differed substantially depending upon whether it was federal or state action at issue. Understanding the Court’s rejection of dual federalism and the underlying reasons for it fatally undermines the historical argument for a return to dual federalism. At the same time, appreciating the full, nuanced history of the Court’s Commerce Clause jurisprudence provides a much needed historical context for assessing the current Court’s preoccupation with and approach to issues of commercial federalism.