University of Minnesota Prof. Steven Ruggles, who won a prestigious MacArthur Fellowship on Wednesday, is the architect of the world's largest population statistics database — an unfathomably sprawling system that details the characteristics of more than 2 billion people who walked the Earth between 1790 and today.

Ruggles, 67, built the Integrated Public Use Microdata Series (IPUMS) in 1993 to guide his research on changing family structures. It has since become the world's largest public database of census microdata, enabling researchers worldwide to analyze social change over time. Scholars have used the data to assess COVID-19 vulnerability, the intersection of residential segregation and employment, and how climate events affect migration.

"I think you can't figure out what's going on now and what's going to go on in the future if you don't know where we came from," Ruggles said of his work as director of the U's Institute for Social Research and Data Innovation. "It's critical to understand people's characteristics in the past if we want to plan for the future."

The fellowship from the John D. and Catherine T. MacArthur Foundation — commonly known as the "genius grant" — is one of the nation's most prestigious intellectual achievement awards.

Studying historical demography became a passion for Ruggles during his undergraduate studies. In his work, he found it difficult to use family structure data covering the 20th century.

That sparked the beginning of IPUMS, which now has 120 to 130 people developing data. In the late 1990s, researchers began including data from other countries and later worked with genealogical organizations to include information dating to the 18th century.

The data allow researchers to examine the impact of large-scale events — such as industrialization — on families.

"We've basically begun to think about what happened with data which we didn't have 30 years ago," he said.

Recently, the expansive data helped social scientists realize they had wrongly assumed that social and economic mobility increased over time, Ruggles said. The opposite was true. It's more difficult for people to climb the ladder of success.

"People are less mobile and they are sticking around closer to where they were born more than they were in the middle of the 19th century," he said.

Ruggles' work is instrumental for other researchers not just across the nation, but around the world, said colleague Phyllis Moen, professor of sociology and former director of the Life Course Center, which operates under Ruggles' institute.

"He's simplified the way we can address large questions and issues that matter for the public good," she said.

At the university, Ruggles "jump-started" population research — analyzing disparity and changes over time, Moen said. Among his colleagues, he's known as a great leader and for creating an environment that allows people to do their best.

"I think of him as an unsung hero of social research," she said. "He's been laboring in the vineyards, so to speak. He made it possible for many people to do research. … He's the perfect choice for the MacArthur grant."

The grant comes with an $800,000 stipend, paid in quarterly installments over five years with no strings attached on how recipients spend the money.

The cash will go right back into IPUMS and sustaining it for researchers, Ruggles said.

"One of the things I'm worried about is the sustainability of the data structure," he said. "This isn't enough money to make a dent in it, but it does give me some time to look at options to sustain what we built."

He noted that 260,000 researchers worldwide rely on IPUMS data for their work and about 2,700 articles are written a year using information from the database. The database presents a sweeping wealth of knowledge, from births and deaths to marital status, family structure, class, race and gender. At a time when researchers are awash with it, Ruggles said it's paramount to ensure that data is freely accessible to all.

"An explosion in the availability of large-scale demographic data has opened new research opportunities and stimulated the development of new methods, resulting in an astonishing acceleration of the pace of discovery," he told the MacArthur Foundation.