In a groundbreaking Cornell-led study illuminating the extensive scope of mass incarceration in the U.S., nearly 1 in 2 Americans have had a sibling, parent, spouse or child spend time in jail or prison—a far higher figure than previously estimated. Led by Peter Enns, associate professor of government, and Christopher Wildeman, professor of policy analysis and management, the study is the first to accurately measure the share of Americans—45 percent—who have ever had an immediate family member jailed or imprisoned for one night or more. The researchers had assumed they would find half that rate.