The decline in youth employment is part of a broader shift in working patterns. Americans are entering the workforce later and staying in it longer than at any time in history. Andrew Sum, a Northeastern University economist and expert in youth employment, points to a remarkable statistic: A decade ago, a 16- or 17-year-old boy was twice as likely to have a job as his 70-year-old grandfather. Today, the grandfather is actually more likely to have a job than the boy. That’s an amazing shift in so short a period of time.

What’s going on? For young adults in their late teens and early 20s, rising rates of college attendance are a big part of the story. But that’s less of a factor for kids still in high school. Some high-schoolers may be opting out of work in order to focus on college application-boosting extra-curricular activities, but the decline in employment has been most pronounced among teens from low-income families, not the middle class. Nor does the minimum wage—often cited as a major barrier to youth employment—appear to be a driving force: Much of the decline came in the early 2000s, when the minimum wage was flat.