St. George Tucker wrote the first extended, systematic commentary on the Constitution after ratification. View of the Constitution of the United States was published in 1803 and served as an important handbook for American law students, lawyers, judges,  jurists and statesmen  for the first half of the 19th century. The following excerpt explains the “supremacy clause.”

SUPREMACY CLAUSE: “This Constitution, and the Laws of the United States which shall be made in Pursuance thereof; and all Treaties made, or which shall be made, under the Authority of the United States, shall be the supreme Law of the Land; and the Judges in every State shall be bound thereby, any Thing in the Constitution or Laws of any State to the Contrary notwithstanding.”

It may seem extraordinary, that a people jealous of their liberty, and not insensible of the allurement of power, should have entrusted the federal government with such extensive authority as this article conveys: controlling not only the acts of their ordinary legislatures, but their very constitutions, also.

The most satisfactory answer seems to be, that the powers entrusted to the federal government being all positive, enumerated, defined, and limited to particular objects; and those objects such as relate more immediately to the intercourse with foreign nations, or the relation in respect to war or peace, in which we may stand with them; there can, in these respects, be little room for collision, or interference between the states, whose jurisdiction may be regarded as confided to their own domestic concerns, and the United States, who have no right to interfere, or exercise a power in any case not delegated to them, or absolutely necessary to the execution of some delegated power.

That, as this control cannot possibly extend beyond those objects to which the federal government is competent, under the constitution, and under the declaration contained in the twelfth article (Tenth Amendment), so neither ought the laws, or even the constitution of any state to impede the operation of the federal government in any case within the limits of its constitutional powers. That a law limited to such objects as may be authorized by the constitution, would, under the true construction of this clause, be the supreme law of the land; but a law not limited to those objects, or not made pursuant to the constitution, would not be the supreme law of the land, but an act of usurpation, and consequently void. (emphasis added)

Mike Maharrey