The United States labor market is closing in on full employment in an economic expansion that just began its 10th year, and yet the real hourly wage for the working class has been essentially flat for two years running. Why is that?

Economists ask this question every month when the government reports labor statistics. We repeatedly get solid job growth and lower unemployment, but not much to show for wages. Part of that has to do with inflation, productivity and remaining slack in the labor market.

But stagnant wages for factory workers and non-managers in the service sector — together they represent 82 percent of the labor force — is mainly the outcome of a long power struggle that workers are losing. Even at a time of low unemployment, their bargaining power is feeble, the weakest I’ve seen in decades. Hostile institutions — the Trump administration, the courts, the corporate sector — are limiting their avenues for demanding higher pay.

Looking at the historical relationship between working-class wages and unemployment, wage growth should be rising about a percentage point faster than it is right now. In June, the Bureau of Labor Statistics reports, wages were growing at a yearly rate of 2.7 percent before inflation.