The large number of people getting trapped in entry-level jobs is at least partly the fault of the overall economy. The share of workers staying in low-wage jobs at least a year rose during the 2008-09 recession and has improved only modestly since then. Other research has found that “job ladders” failedin the wake of the recession: Workers were forced into jobs they were overqualified for and then weren’t able to move up into better jobs the way they would during better economic times. And more generally, weak wage growth has been a hallmark of this recovery for workers across the economic spectrum.

But the recession isn’t the entire explanation. Even before the economy collapsed, workers were spending longer in minimum-wage jobs. The decline in manufacturing is likely part of the story: Factories were a key source of well-paying jobs for men without a college education, a group that has become substantially more likely to work in low-wage occupations in recent years. The broader decline of private-sector unions, which helped workers negotiate for higher pay, also likely played a role, argued Cherrie Bucknor, who has studied the changing low-wage workforce for the Center for Economic and Policy Research, a liberal think tank.

A generation ago, someone like (Anthony) Kemp — a widower (in Oak Park, Ill.) who never completed high school — might have held a union job in a factory. Today, he is frying chicken for $8.25 an hour with little hope of advancement.