The decline of marriage over the past half century ranks among the most profound demographic transformations in American demographic history. This paper puts recent change into historical context by providing new estimates of long-run trends in marriage. I then describe change in the family economy and explore the impact of economic changes on marriage behavior. I conclude with a discussion of cultural and structural explanations for change and their implications for the future.

The IPUMS-International partnership is led by the University of Minnesota Population Center in consortium, at present, with 101 official statistical agencies that have endorsed uniform protocols for world-wide access to microdata free-of-cost (https://international.ipums.org/international/international_partners.shtml). In 2014, the partnership is celebrating its fifteenth year with the launch of 259 integrated, confidentialized samples representing 79 countries (82% of the worlds population) and totaling 561,622,889 person records. More than 9,000 researchers have made over 50,000 extracts from the IPUMS-International database and published nearly a thousand papers, reports, dissertations and books using the microdata. Research output will continue to grow as 2010 round census samples and other types of microdata (surveys on demography, health, labor force, etc.) are integrated into the IPUMS dissemination system. Through the IPUMS partnership the value of census microdata is enhanced for both producers (official statisticians) and users (researchers and policy makers) in three important ways: 1) Dissemination: one portal with a single set of rules and internet browser tools provides access to microdata for all researchers, regardless of country of residence; 2) Security: privacy and confidentiality are protected by rigorous technical, administrative and legal protocols; and 3) Usefulness: both metadata and microdata are integrated to preserve the definitions and concepts in each census to facilitate good use.

This article critically evaluates the available data on trends in divorce in the United States. We find that both vital statistics and retrospective survey data on divorce after 1990 underestimate recent marital instability. These flawed data have led some analysts to conclude that divorce has been stable or declining for the past three decades. Using new data from the American Community Survey and controlling for changes in the age composition of the married population, we conclude that there was actually a substantial increase in age-standardized divorce rates between 1990 and 2008. Divorce rates have doubled over the past two decades among persons over age 35. Among the youngest couples, however, divorce rates are stable or declining. If current trends continue, overall age-standardized divorce rates could level off or even decline over the next few decades. We argue that the leveling of divorce among persons born since 1980 probably reflects the increasing selectivity of marriage.

This article describes an explosion in the availability of individual-level population data. By 2018, demographic researchers will have access to over 2 billion records of accessible microdata from over 100 countries, dating from 1703 to the present. Another 2 to 4 billion records will be available through restricted-access data enclaves. These new resources represent a new kind of data that will enable transformative research on demographic and economic change and the spatial organization of society.

Fifty years ago, census microdata were available for only a handful of countries and trans-border access was difficult for all but a few. Now, from www.ipums.org, many decades of census microdata for much of the globe are readily accessible anywhere, free of cost to researchers and students - regardless of country of birth, residence, or citizenship. As of late - 2013, 238 samples representing 74 countries, totaling more than one half billion person records and encompassing more than four fifths of the world's population are available to more than 7,000 registered researchers worldwide. Pioneers of demography developed national and even regional databases for analyzing census microdata (Ruggles 2013), but it is IPUMS that developed the first integrated system for global access. The IPUMS big data revolution, foretold a decade ago (McCaa and Ruggles 2002), has arrived, but is not yet complete. 50 years hence it is likely that almost all census microdata around the globe will be integrated and accessible via multiple systems of access using application programming interfaces (API).The revolution has already sparked much new research. According to a former president of the Population Association of America, students of the Big Census Data Revolution, specifically those with analytical experience using integrated census microdata, enjoy advantages for internships and employment at the World Bank and similar agencies (Meier, Lam, and McCaa 2011). Likewise, Dot-Coms beckon as a new jobs frontier opens for savvy Big Data users (Lohr, 2012:B2).

Terra Populus, part of NSFs new DataNet initiative, will develop organizational and technical infrastructure to integrate, preserve, and disseminate data describing changes in the human population and environment over time. A plethora of high-quality environmental and population datasets are available, but they are widely dispersed, have incompatible or inadequate metadata, and have incompatible geographic identifiers. The new infrastructure will enable researchers to identify and merge data from heterogeneous sources to study the relationships between human behavior and the natural world. Terra Populus will partner with data archives, data producers, and data users to create a sustainable international organization that will guarantee preservation and access over multiple decades.

An explosion of new data sources describing historical family composition is opening unprecedented opportunities for discovery and analysis. The new data will allow comparative multilevel analysis of spatial patterns and will support studies of the transformation of living arrangements over the past 200 years. Using measurement methods that assess family choices at the individual level and analytic strategies that assess variations across space and time, we can dissect the decline of patriarchal family forms in the developed world and place Northwest Europe and North America in global comparative context.

Many statistical offices recognize the need for enhancing access to census microdata. High costs, challenging risks, and low rewards are substantial obstacles to going-it-alone. An economical, essentially cost-free solution, endorsed by more than 90 National Statistical Offices, is offered by the IPUMS-International project. This paper discusses ten ways the project enhances access and adds value to census microdatagrouped into four categories: 1. statistical confidentiality (security, disclosure protections, managing access), 2. Integration (comprehensive source documentation, integrated metadata, integrated, pooled microdata, IPUMS-I constructed variables), 3. Dissemination (free, trans-border access, custom-tailored extracts), and 4. ethics (statistical transparency, academic freedom, reduction of risks of fraud/mis-representation, and sharing of research findings). Statistical agencies not yet participating in the IPUMS-International initiative are invited to do so. Those already participating are encouraged to entrust 2010 round census microdata to the project in a timely manner.

IPUMS-International disseminates population census microdata at no cost for 69 countries. Currently, a series of 212 samples totaling almost a half billion person records are available to researchers. Registration is required for researchers to gain access to the microdata. Statistics from Google Analytics show that IPUMSInternationals lengthy, probing registration form is an effective deterrent for unqualified applicants. To protect data privacy, we rely principally on sampling, suppression of geographic detail, swapping of records across geographic boundaries, and other minimally harmful methods such as top and bottom coding. We do not use excessively perturbative methods. A recent case of perturbation gone wrong the household samples of the 2000 census of the USA (PUMS), the 20032006 American Community Survey, and the 20042009 Current Population Survey, an empirical study of the impact of perturbation on the usability of UK census microdatathe Individual SARs of the 1991 census of the UK, and a mathematical demonstration in a timely compendium of statistical confidentiality practices confirm the wisdom of IPUMS microdata management protocols and statistical disclosure controls.

This study uses a new source of linked census data (N = 6,734) to test theories proposed to explain the high intergenerational coresidence in 19th-century America. Was it a system of support for dependent elderly, or did it reflect intergenerational interdependence? I focus on transitions from middle age to old age, and I assess key predictors of family transitions, including widowhood, retirement, disability, migration, and wealth. The results show that adverse events precipitated changes in the headship of intergenerational families but did not increase the likelihood of residing in an intergenerational family. The findings suggest that 19th-century intergenerational coresidence was not principally a means of old-age support; more often, probably, there was a reciprocal relationship between generations.

In this paper, we investigate the relationship of male and female economic opportunity to marriage formation in 2000, examining how relationships vary with race and ethnicity. To address these issues, we carry out multi-level analysis of the effects of local economic conditions on the marriage decisions of young men and women. We will compare results obtained using the 5% sample of Census 2000 from the Integrated Public Use Microdata Series (IPUMS) with those from an analysis of restricted access census files available only through Census Bureau Research Data Centers (RDCs). The internal files allow the identification of small geographic regions to measure local economic conditions. This analysis will help gauge the value of the restricted access data by presenting a benchmark using public data.

The Minnesota Population Center (MPC) provides aggregatedata and microdata that have been integrated and harmonized to maximize crosstemporal and cross-spatial comparability. All MPC data products are distributed free of charge through an interactive Web interface that enables users to limit the data and metadata being analyzed to samples and variables of interest to their research. In this article, the authors describe the integrated databases available from the MPC, report on recent additions and enhancements to these data sets, and summarize new online tools and resources that help users to analyze the data over time. They conclude with adescription of the MPCs newest and largest infrastructure project to date: a global population and environment data network.

The Minnesota Population Center (MPC), through the IPUMS-International census microdata project, archives the world's largest stock of census microdata and documentation. A decade of labor assiduously scouring local, national, regional, and international archives on every continent is beginning to bear fruit. Microdata for over 350 censuses for more than 120 countries are safely ensconced in the MPC digital archives. Metadata from more than 900 censuses are catalogued and now being disseminated world-wide without cost in cooperation with National Statistical Institute(NSI) partners and the Integrated Health Survey Network, using the latest international standards for electronic metadata. 5,000 researchers representing more than ninety countries are registered to access confidentialized, integrated microdata without payment and with complete academic freedomthanks to a uniform licensing agreement endorsed by almost one-hundred NSIs. Integration lowers the barriers to entry and facilitates comparative research over space and time.For the future, we plan to integrate and disseminate confidentialized samples of the 2010 round censuses of the sixty-two countries already represented in the database. Samples of an additional 20-30 countries will be released to the global scientific community as time and resources permit. New initiatives are also planned: boundary files for GIS applications, an on-line tabulator forregistered researchers, a secure enclave offering access to full-count microdata at the MPC and perhaps virtual enclaves for partners world-wide with certified secure sites. Several NSI partners have already granted assent for constructing a pilot at the MPC. Before the end of this year, thanks to major funding from the National Science Foundation (USA), a new project, TerraPop, begins--an initiative to combine population microdata with climate and land cover data.

In the last decade, a revolution has occurred in access to census microdata for social and behavioral research. More than 325 million person records (55 countries, 159 samples) representing two-thirds of the worlds population are now readily available to bona fide researchers from the IPUMS-International website: www.ipums.org/international hosted by the Minnesota Population Center. Confidentialized extracts are disseminated on a restricted access basis at no cost to bona fide researchers. Over the next five years, from the microdata already entrusted by National Statistical Office-owners, the database will encompass more than 80 percent of the worlds population (85 countries, ~100 additional datasets) with priority given to samples from the 2010 round of censuses. A profile of the most frequently used samples and variables is described from 64,248 requests for microdata extracts. The development of privacy protection standards by National Statistical Offices, international organizations and academic experts is fundamental to eliciting world-wide cooperation and, thus, to the success of the IPUMS initiative. This paper summarizes the legal, administrative and technical underpinnings of the project, including statistical disclosure controls, as well as the conclusions of a lengthy on-site review by the former Australian Statistician, Mr. Dennis Trewin.

In this article, the authors describe a new data infrastructure project being developed at the Minnesota Population Center. The Integrated Spatio-Temporal Aggregate Data Series (ISTADS) will make it easier for researchers to use publicly available aggregate data for the United States over a time span that covers virtually the entire life of the nation: 17902012. In addition to facilitating access and ease of use, ISTADS will facilitate the use of thesevarious data sets in mapping and spatial analysis.

The age of parents at the birth of their children may have profound implications for the subsequent lifecourse of parents, the functioning of the family, and for child health and well-being. Using historicalcensus data from the Integrated Public Use Micro Series, this research explore three dimensions ofparental age: chronological age (Martin et al. 2009), social age (Mare and Tzeng 1989; Eliason et al.2009), and relationship age (Bachu 1999) from the early 1900s until 2008. Little is known about longtermhistorical shifts in these dimensions of age, and to our knowledge, there has been no systematicinvestigation of their interdependence. This research addresses the transformation of family life byinvestigating historical change in three dimensions of parental age and the ways in which thedimensions are woven together.

This note revisits the author's June 2009 PDR article, Reconsidering the Northwest European family system. Using an array of contemporary and historical census microdata from around the world with simple controls for agricultural employment and demographic structure, I detected no significant differences in complex family structure between nineteenth-century Western Europe and North America and twentieth-century developing countries. This article adds two new measures designed to detect stem families and joint families. The results suggest that Western Europeans and North Americans have had a long-standing aversion to joint family living arrangements, and that this pattern cannot be easily ascribed to demographic and economic conditions.