This article presents the first comprehensive early history of Congress’s power “to regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes.” In seeking to discover the original meaning of the Commerce Clause (CC), scholars have focused almost exclusively on the records of the Conventions that drafted and ratified the Constitution. Although I have also examined these sources, I have added an exhaustive survey of legal materials that have been largely ignored: the CC’s interpretation and application by Congress, the executive branch, and the Supreme Court from 1789 to 1829. Those documents establish that the CC imposed two requirements. First, Congress could regulate only “commerce”—voluntary sales of goods and services and accompanying activities (such as manufacturing and agriculture) geared toward the market. Second, such “commerce” had to (1) be “with” a foreign country or Indian Tribe, or (2) have a measurable impact in more than one state. These limitations are critical because the Framers did not grant Congress general authority, but rather carefully enumerated its powers and left all others to the states or “We the People.” My two-step framework precisely tracks the CC’s language, reinforces the Constitution’s structure, and faithfully reflects the Convention and Ratification debates and the federal government’s early implementation of the CC. By contrast, alternative historical accounts are unpersuasive. On the one hand, Justice Thomas and scholars such as Richard Epstein and Randy Barnett have contended that the Supreme Court from 1836–1936 correctly interpreted the CC as authorizing Congress to regulate as “commerce” only the sale or transportation of goods. This narrow view, however, ignores that the CC allowed Congress to reach all other market-oriented activities, such as the production of goods and compensated services like banking and labor. On the other hand, the modern Court has upheld CC legislation as long as Congress could have had a rational basis for determining that the regulated activity, considered in the aggregate, substantially affects interstate commerce. Every statute has passed this test, with a few trivial exceptions. The Court has thereby allowed Congress to exercise unrestrained discretion, without ever justifying this result in light of the CC’s original meaning. Akhil Amar and Jack Balkin have attempted to do so by making two arguments. First, the word “commerce” signified “intercourse”—all interactions, not merely economic but also social and political. Second, the phrase “among the states” authorized Congress to legislate in the national interest, especially when states acting separately could not adequately handle an issue. Accordingly, Amar and Balkin claim that Congress can intervene whenever it concludes that it should address any interactions which extend beyond one state’s boundaries and which create problems that can only be resolved at the national level. The foregoing approach would sustain virtually all CC statutes. Unfortunately, Professors Amar and Balkin have not cited anyone from 1787 to 1829 who stated or implied that the CC empowered Congress to reach all interactions—as contrasted with merely “commercial” (i.e., market-based) activities—that had out-of-state ramifications. This void forces these scholars to resort to two strained claims. First, they assert that the CC may have incorporated an uncommon usage of “commerce” as “intercourse” found in various British linguistic, literary, philosophical, and religious works. However, most of these documents were published long before 1787; none concerned the legal meaning of “to regulate commerce;” and no one who participated in America’s Constitution-making process ever alluded to this unusual usage. Second, Amar and Balkin maintain that early federal government officials construed Congress’s power “to regulate commerce with Indian Tribes” as encompassing all “intercourse” with such Tribes—and that therefore this same broad interpretation should apply in the interstate context. On the contrary, the evidence overwhelmingly demonstrates that these officials faithfully adhered to the Framers’ intent and the Ratifiers’ understanding that (1) the Indian Commerce Clause authorized Congress to address only market-oriented activities (such as trade) with the Tribes; and (2) other constitutional provisions and principles conferred exclusive federal authority to deal with all other matters involving Indians, most notably warfare, treaties, and crimes. Moreover, laws governing the unique field of Indian affairs shed little light on Congress’s distinct power to regulate interstate commerce. Rather, the directly relevant legal materials—federal legislation, executive practice, and Court cases on the CC from 1789 to 1829—reveal the universal understanding that the CC was confined to market-based activity. Remarkably, Professors Amar and Balkin do not mention, much less grapple with, any of this historical evidence. In short, an objective analysis of the Commerce Clause’s text and surrounding history leads to the conclusion that the Amar/Balkin “intercourse” idea is too expansive, whereas the Thomas/Epstein/Barnett “trade and transportation of goods” thesis is too narrow. Rather, Congress could regulate all market-directed actions that transcended state borders