In debates about reorienting the American revenue system, nearly everyone assumes the Constitution is irrelevant. With few exceptions, the tax provisions in the original Constitution - particularly the direct-tax apportionment rule and the uniformity rule - have been interpreted to be paper tigers. And in only one major case has the Sixteenth Amendment, which excepts "taxes on incomes" from apportionment, been held to limit congressional power.Rejecting conventional wisdom, this Article argues that some consumption taxes would violate constitutional norms. The Article focuses on the requirement that “direct taxes” be apportioned among the states on the basis of population. From a study of founding-era debates, the Article concludes that “direct taxes” has a meaning with contemporary relevance: Direct taxes are not duties, imposts, or excises, and they are imposed by the national government on individuals rather than on the states. Along the way, the Article criticizes Hylton v. United States, in which the Supreme Court considered the meaning of “direct taxes” in 1796, and argues that the Court did better in Pollock, which struck down the 1894 income tax.Applying this historical understanding, the Article examines several proposed national consumption taxes. It concludes that a value-added or sales tax would be an indirect tax not subject to apportionment, but that the so-called “flat tax” or the unlimited savings allowance (USA) tax would be a direct tax. Moreover, the Article argues that such a direct-consumption tax should not escape apportionment as a “tax on incomes” under the Sixteenth Amendment.