This section, as amended by Section 2 of the Fourteenth Amendment, requires, for the purpose of apportioning the House of Representatives, that a census be taken of the whole number of persons in the nation. Congress has followed the Constitution’s command, even extending the census into territories and appending long lists of additional inquiries, although it is questionable as to what power Congress possesses to ask non-apportionment-related questions.

The central question regarding the original meaning of this section is whether the Constitution requires that this census consist only of an actual counting of individuals or whether the national government may rely on estimates of the national population to apportion the House. There was no direct discussion at the Constitutional Convention regarding whether there should be an actual count. The Committee of Detail’s draft of the section stated that the number of inhabitants “shall . . . be taken in such manner as . . . [Congress] shall direct.” That phrasing was modified to “as they shall by Law direct,” and the Committee of Style subsequently added the phrase “actual Enumeration.”

Those who contend that this section allows the use of estimates of the population argue that this phrase “actual Enumeration” likely means the most accurate possible calculation. When this phrase, so defined, is read together with the words “in such Manner as they shall by Law direct,” they conclude that the Framers intended to grant Congress complete discretion to choose whatever method of census taking they thought would result in the most accurate calculation of population, including the use of estimating methods. Alternatively, the word “actual” refers to the first census to be conducted three years after the meeting of the first Congress, as opposed to the less formal enumeration the Framers relied upon in apportioning the first and second Congresses.

Those who maintain that the phrase “actual Enumeration” means actual counting of individuals as opposed to the use of estimating methods argue, as Justice Antonin Scalia did in Department of Commerce v. United States House of Representatives (1999), that the words mean “counting ‘singly,’ ‘separately,’ ‘number by number,’ ‘distinctly.’” The distinction between actual counting and estimating was well known and thoroughly discussed both in debates in eighteenth-century English politics and in controversies between the American colonies and England. Indeed, the participants in these debates used the precise terms at issue; those who criticized the use of estimates in calculating population figures demanded instead that an enumeration—an actual count—be taken.

In The Federalist No. 36, Alexander Hamilton, in attempting to reassure his audience that the population figures upon which taxation would be based would not be subject to political manipulation, stated that “an actual census or enumeration of the people must furnish the rule, a circumstance which effectually shuts the door to partiality or oppression.” The Census Act of 1790, establishing the first census, required an actual counting; census takers were required to swear an oath to “truly cause to be made, a just and perfect enumeration and description of all persons resident within [their] districts.”

The Supreme Court, after avoiding the constitutional question in previous cases challenging the use of advanced statistical methods, decided the question of whether an actual counting is required in Utah v. Evans (2002), a case involving the use of a methodology that infers that households not actually counted in the census have the same population characteristics as their geographic neighbors that were counted. Justice Stephen Breyer, writing for the majority, concluded that the Framers “did not write detailed census methodology into the Constitution,” and therefore methods, such as the one used in this case, that are based on inference and not actual counting are constitutionally valid. Justice Clarence Thomas, writing in dissent, lamented the Court’s decision. He concluded: “Well familiar with methods of estimation, the Framers chose to make an ‘actual Enumeration’ part of our constitutional structure. Today, the Court undermines their decision, leaving the basis of our representative government vulnerable to political manipulation.”