future censuses. Specifically, the panel considered the possibility that designs that made use of sampling and administrative records, which might offer cost savings and other benefits for the census, could satisfy data requirements for reapportionment and redistricting.
As noted above, the U.S. Constitution mandates the conduct of an "enumeration" every 10 years for the purpose of reapportionment of the U.S. House of Representatives.2 The interpretation of the word enumeration is obviously key to an assessment of whether census designs that involve sampling or administrative records could serve this fundamental purpose. A second important consideration is that reapportionment must be effected simultaneously for the entire country—one cannot reapportion in some areas in one year and in other areas in another.
A legal review prepared by the Congressional Research Service (Lee, 1993) concludes that, for the purpose of reapportionment, there needs to be an attempt to account for every inhabitant in the country: a sample census, no matter how large, cannot satisfy the constitutional requirement.3 Similarly, "rolling census" designs, in which different parts of the population are surveyed each year without even a minimal census of the entire population at any one time, would not satisfy the requirement. (The rolling census designs proposed by Horvitz, 1986, and Kish, 1981, 1990, are in this category.) Other rolling census designs, namely, those that do include a minimal census every tenth year, would satisfy the constitutional requirement. (The designs proposed by Herriot et al., 1989, and Alexander, 1993, are of this type; see Chapter 6 for further discussion of the potential and problems of rolling census or continuous measurement designs that include a minimal decennial census together with rolling surveys.)
Lee (1993) draws the conclusion that an attempt at a complete count is constitutionally required from a review of the meaning of the word enumeration at the time the Constitution was adopted and subsequent legislative and judicial history.4 In particular, two sections of Title 13 of the U.S. Code (which pertains to the Census Bureau) address the topic of sampling in the decennial census. Section 195, adopted in 1957, states that "except [emphasis added] for the determination of population for purposes of apportionment of Representatives in Congress among the several States, the Secretary shall, if he considers it feasible, authorize the use of the statistical method known as 'sampling' in carrying out the provisions of this title." Section 141(a) appears to be more liberal, in that it authorizes the secretary of commerce to take a decennial census every 10 years "in such form and content as he may determine, including the use of sampling