Age at first marriage increased dramatically between 1960 and 1990, especially among blacks. The median age at first marriage among black men went from 22.5 to 28.6, and among women from 20.4 to 27.8. These increases are among the most rapid ever recoded for any historical population. Census 2000 reveals a dramatic and unexpected surprise: although median age at first marriage continued to rise for black women, it declined sharply for black men (see Figure 1). The census data indicate that black men are now marrying a year younger than black women. This paper will explore the reasons behind this unusual pattern. In particular, we will assess the effects of changing age intervals between spouses among black married couples; changing patterns of intermarriage between blacks and other racial groups; underenumeration of single black men; and changes in the income distribution of young black men.

The quantity and character of internal migration in the American past is a contentious historiographical issue. Over a century ago, Frederick Jackson Turner pointed to westward migration as a safety valve that profoundly affected the nature of the Republic. With the closing of the frontier, Turner predicted, the population flow to the West would decline.1 Turner's twentieth-century critics argued that the greatest American population movement was not westward expansion, but rather urbanization, which accelerated throughout the nineteenth and twentieth centuries. Beginning in the 1960s, social historians using new quantitative approaches fleshed out the critique of Turner, arguing that high migration to and between urban areas in the nineteenth century did not result in improved economic opportunity.This article uses new evidence to reevaluate internal migration in the American past. Our three major findings are consistent with Turner's interpretation. First, we identify a U-shaped pattern of change: the nineteenth century had the highest overall levels of migration, followed by a decline in the first half of the twentieth century and a resurgence after World War II. Thus, by the time Turner wrote about the closing of the frontier, a dramatic decline in geographic mobility was already under way. The highest mobility in American history occurred during the first half of the nineteenth century, and there was a steady decline in interstate mobility until well into the twentieth century. Second, we show that the high levels of nineteenth-century migration resulted from long-distance westward migration to farms, whereas the high migration of the late twentieth century can be ascribed to white suburbanization and black Patricia Kelly Hall is a doctoral candidate at the University of Minnesota, and Steven Ruggles is Distinguished McKnight University Professor of History and Population Studies at the University of Minnesota. migration to northern cities. Finally, we look briefly at the relationship between geographic mobility and social mobility and find evidence suggesting that migration may have improved economic opportunity.

The 1880 US population database contains records for the over 50 million individuals enumerated in the census. This unique data set is the result of collaboration between the Minnesota Population Center (MPC) and the Church of Jesus Christ of Latter-day Saints (LDS). To make census data available to genealogists. LDS volunteers transcribed the characteristics of all US residents in 1880. The MPC verified and corrected this transcription, in exchange for the right to disseminate the resulting database for scholarly and educational purposes. The authors consider editing and coding procedures and a range of problems: missing and incorrect geographic identifiers, data-processing errors, duplicate and missing cases, and inaccurate breaks between households. They also classify variables according to standardized coding systems, making the database compatible with the Integrated Public Use Microdata Series (IPUMS).

Integrated Public Use Microdata Series-International (IPUMS-International) is an effort to inventory, preserve, harmonize, and disseminate census microdata from around the world. IPUMS-International aims to convert census data from five continents into a uniformly coded and fully documented data series. Nearly all countries included in the data series contribute data from multiple census years. The project uses the same principles and methods that underlie the successful IPUMS-USA model. The data are distributed free of charge via a Web-based data extraction system. Use of the data is restricted to scholarly and educational purposes. The project is conceived as part of a larger enterprise to make the world's microdata available to researchers, encouraging cross-national research with a temporal dimension.

Census microdata are an invaluable resource for social science and policy research. Until recently National Statistical Institutes (NSI) permitted little use of these data. This paper describes the IPUMS-International project (www.ipums.org/international), a global collaboratory of NSIs to anonymize, harmonize and provide access on a restricted basis to extracts of integrated census microdata samples. Access is limited to bona fide scientists with demonstrated research need who agree to abide by the conditions of use license. Custom-tailored extracts are delivered, at no charge via the Internet. At present forty official census agencies have formally ratified the IPUMS-International protocols: Argentina, Austria, Belarus, Brazil, Bulgaria, Chile, China, Colombia, Costa Rica, Czech Republic, Dominican Republic, Ecuador, El Salvador, France, Germany, Ghana, Greece, Guatemala, Honduras, Hungary, Israel, Kenya, Madagascar, Mexico, Netherlands, Nicaragua, Palestinian Authority, Panama, Paraguay, Peru, Portugal, Puerto Rico, Romania, Slovenia, Spain, Tajikistan, the United States, Turkmenistan, United Kingdom ,Venezuela, and Vietnam. National Statistical Institutes interested in additional information about the initiative are invited to contact Dr. Robert McCaa (rmccaa@umn.edu).

Abstract. This paper describes a proposal for the Asia and Pacific Region to develop a restricted access web-site providing anonymized, integrated census microdata for social science and policy research. With funding by the U.S. National Science Foundation and the National Institutes of Health we propose to build on the successful IPUMS-International protocols www.ipums.org/international). This initiative is a global collaboratory in partnership with the Official Statistical Authority (OSA) in each member-state. Two region-wide efforts, one for Europe and the other for the Americas, are now underway with a total of 33 countries participating. In the Asia region, integrated census microdata for Vietnam first became available in May 2002 and China in 2003. Access to integrated microdata is restricted to bona fide university scientists with demonstrated research need who agree to abide by the conditions of use license. Custom-tailored extracts are delivered, at no charge via the Internet. At present more than forty official census agencies have formally ratified the IPUMS-International protocols. Statistical Agencies of the Asia and Pacific Area interested in joining a region-wide initiative are invited to contact Dr. Robert McCaa (rmccaa@umn.edu).

Focuses on the National Historical Geographic Information System (NHGIS), a project to make aggregate census data accessible within a Geographic Information System framework for historical population research in the U.S. Range of technological innovations attributed to the feasibility of NHGIS; Key to the accessibility of census summary files; Work components of the project.

This article has three goals. First, it explores the effects of changes in census definitions and concepts on the measurement of living arrangements. As part of this analysis, the authors develop new estimates of the number of households and group quarters in each census year since 1850. Second, they evaluate the existing aggregate statistical series on family and household composition, with particular attention to problems in the measurement of subfamilies. Finally, they describe data and methods for developing a consistent set of statistics for the period since 1850 and offer recommendations for the coherent measurement of family and household composition.

The 1880 U.S. population database contains records for the over 50 million individuals enumerated in the census. This unique data set is the result of collaboration between the Minnesota Population Center (MPC) and the Church of Jesus Christ of Latter-day Saints (LDS). To make census data available to genealogists, LDS volunteers transcribed the characteristics of all U.S. residents in 1880. The MPC verified and corrected this transcription, in exchange for the right to disseminate the resulting database for scholarly and educational purposes. The authors consider editing and coding procedures and a range of problems: missing and incorrect geographic identifiers, data-processing errors, duplicate and missing cases, and inaccurate breaks between households. They also classify variables according to standardized coding systems, making the database compatible with the Integrated Public Use Microdata Series (IPUMS).

The North Atlantic Population Project (NAPP) brings together complete-count census data from late-nineteenth-century Canada, Great Britain, Iceland, Norway, and the United States into a single harmonized database. When released in 2005, the final version of the database will include the records of nearly 90 million people. The project will consistently code all variables across the different countries, while still retaining important national variation in census questions and responses. The authors provide a brief history of the project, discuss the main issues involved in creating a harmonized international census database, and outline the methodological and research opportunities the completed database will provide for scholars.

Analysis of long-run changes in the living arrangements and economic well-being of the aged is limited by the consistent data sources across time and space. Some fragmentary evidence on the living arrangements of the aged in several European and North American countries before the mid-twentieth century is summarized in Table 1. The numbers should be interpreted cautiously. The earliest estimates are especially suspect, since we generally lack information about the enumeration procedures or completeness of the surviving pre-nineteenth century listings of inhabitants. Even in the nineteenth century, there was significant variation in census concepts and definitions among countries and across time (Ruggles and Brower, forthcoming). Moreover, the processing of the existing historical data has not followed standardized procedures from study to study, and we have little information of the representativeness of the local studies. Therefore it would be premature to make too much of the apparent trends and differences shown in Table 1. Despite all of these qualifications, however, we can be confident that prior to the twentieth century most elderly persons in Europe and North America resided with their children and that residing alone was extremely rare.