ABSTRACT
The primary purposes for census-taking vary across nations. For the majority, censuses are the source of information on the migrant stock, but certain countries with population registers already have excellent data and censuses are not necessary. For the United States, the census is constitutionally mandated every 10 years for purposes of apportioning political representation among the states according to the distribution of the population. Just as dramatic changes occurred over time in implementing this count as technologies evolved from hand calculations and early tabulating machines to efficient, high capacity computers, the US Census Bureau’s mission of providing timely, relevant, and quality data about the people and economy of the United States has evolved to include not only the crucial topics of people, housing, business, and governments, for which the major resource has historically been the decennial census of population and housing, but also information from other sources (surveys, administrative statistics, and other information), such as through the Statistical Abstract annual series. The US 2010 Census is the re-engineered census, with the American Community Survey (ACS) designed for collecting detailed social and economic characteristics nationally and subnationally on a continuous basis. With respondent participation on a mandatory basis, the ACS was gradually implemented and fully fielded by 2010. Similarly, Canada initiated the National Household Survey (NHS) in conjunction with the 2011 Census, for which participation is voluntary. Censuses include persons according to residence rules-de jure criteria, or legal residence, or de
facto criteria, or “usual residence,” the place where a person lives and sleeps most of the time or the place they consider their usual residence. Thus, the US census with de facto residence rules includes unauthorized residents as counted in their usual place of residence in the United States. Mexico’s census is by de jure criteria, thus encompassing those migrants sojourning north of the border. China’s 2010 census counted residents at their usual place of residence rather than according to hukuo, place of household registration, and this marked the first application of this residence criterion and first inclusion of international migrants. Residence rules for US national surveys, the ACS and the Current Population Survey (CPS)
differ from the decennial census, with more inclusiveness of the working population and, implicitly, such special populations as temporary migrants and unauthorized residents. Conducted monthly,
the CPS gathers employment and labor force participation data, and the March interview contains supplemental social and economic characteristics. The CPS rule is a version of usual residence that includes everyone in a housing unit who considers the unit as their usual residence or who has no other usual residence plus any temporarily absent individuals for whom the unit is considered usual residence. The ACS concept of residence is “current residence” with everyone interviewed who is in the housing unit on the day of interview who is living or staying there for more than 2 months, regardless of whether or not they maintain a usual residence elsewhere, or who does not have a usual residence elsewhere. If a person who usually lives in the housing unit is away for more than two months at the time of the survey contact, he or she is not a current resident of that unit. This rule recognizes that people can have more than one place where they live or stay over the course of a year, and for those whose residence changes seasonally, such as migrant groups, these conceptual differences may affect where persons are counted in time. Most countries have had a complete census, typically on a periodic basis, such as every ten
years in years ending in “0” or “1,” for a long period as in the case of the United States or a shorter period (1990-2010) as in the case of China, or every five years as in Canada. Nationally representative surveys often augment census-taking. China conducts a population sample census in years ending in “5.” Census-taking is subject to change for reasons of costs, privacy concerns, and various crises. Censuses may be postponed, as were the 2000 round censuses until 2005 or 2006 for Nicaragua, Colombia, Peru, and El Salvador. The UN provides technical and financial assistance in national censuses in order to enhance the value of data for the international community. Temporal comparability may differ over time for several reasons. Migration is a key component in demographic change for a specific population and in
changing the contour of the world population. In the US case, international migration events are outnumbered by internal migration events, due to job mobility, individual preferences, rural-urban shifts, and economic restructuring, but international migration contributes to population growth. In recent decades, industrial expansion in China has resulted in a large “floating population” of workers living near those industrial centers, but those population shifts were not easily captured with hukou-based census-taking. Considerable population growth occurred in Mexico near maquiladoras located at the US-Mexico border. Upon the December 14 2010 release of the first results from the US 2010 Census, the US
population count (308.7 million) seemed much as anticipated based on comparison with the middle estimate (308.5 million) from demographic analysis (US Census Bureau 2010). A decade ago, the 2000 census count showed the greatest national population increase ever and increased populations for each of the 50 states, was higher than the demographic estimate by 6 million, 2 million more than the 1990 census net undercount of 4 million, and sparked immediate reassessment of net immigration for the 1990s. The number of unauthorized residents in 2000 was estimated to be substantially greater than in 1990 with the increase happening in the late 1990s (Bean et al. 2001). Again emphasizing the value of census analysis for understanding migration, regular and irregular, the Mexican Census 2010 count was considerably higher than expected, leading to speculation that migration into the United States over the decade had been less than assumed.
