“Over the past five decades, Middle America has been stagnant in terms of its economic growth,” said Mark Rank, a professor of social work at Washington University in St. Louis. In 1973, the inflation-adjusted median income of men working full time was $54,030. In 2016, it was $51,640 — roughly $2,400 lower. A big chunk of that group — white working-class men — formed a critical core of support for Mr. Trump, who spoke to their economic anxieties and promised changes in trade, immigration and tax policies as a solution.
As in an Agatha Christie mystery, the potential culprits behind the long-term trends are many — global competition, technological advances, trade imbalances, a mismatch of skills, the tax system, housing prices, factory shutdowns, excessive regulation, Wall Street pressure, the erosion of labor unions and more. Most of the suspects, if not all, are likely to have played some role.
But the forces undermining the middle class may reach back farther than many economists have thought. The latest evidence comes from a group of researchers at universities and the Social Security Administration who have been tracking the earnings of hundreds of millions of individuals over their careers.
Starting with 1957, the team looked at actual earnings during the prime working years — the ages of 25 to 55. For a while, it saw a clear pattern: Younger men could expect to make more over their lives than older…