Consider the formative experiences of adults 30 and younger. For them, the Cold War exists only in history books—which they didn’t necessarily read. High schools in only 31 states require a yearlong U.S. history course. Throughout their adolescence and young adulthood, they have seen their country embroiled in Middle Eastern wars triggered by the terrorist attacks on Sept. 11, 2001. Intelligence shortfalls and security failures opened the door to these attacks; outright intelligence failures paved the way for the invasion of Iraq; and the inability of three administrations to define clear, achievable goals in Afghanistan explains why today’s 18-year-olds have spent their entire lives with American troops in Kabul and Kandahar.

Next came the financial collapse of 2008 and the ensuing 2007-09 recession, the deepest downturn since the 1930s. As today’s 30-year-olds entered college that fall, they experienced sharply rising tuition as cash-strapped state governments slashed aid to public higher education, forcing them and their families to assume unprecedented amounts of student debt. They emerged from college to find a depressed labor market that forced many to take low-paying jobs that made no use of the skills they had acquired. They struggled to repay their loans. They responded by postponing marriage and home purchases, and returned in record numbers to live with their parents.

Even as the economy has improved in recent years, many young Americans haven’t felt the benefits.