Economists point to another indicator to help explain the persistence of low wages in a climate of low unemployment: sluggish productivity. American businesses and workers are not getting more dynamic, more innovative, and more efficient—at least not like they were in the 1990s or the 1960s. That has the effect of smothering wage growth. “Wage growth feels low by historical standards and that’s largely because productivity growth is low relative to historical standards,” said Mark Zandi, the chief economist at Moody’s Analytics. “Productivity growth between World War II and up through the Great Recession was, on average, 2 percent per annum. Since the recession 10 years ago, it’s been 1 percent.” Given those statistics, the sluggish pace of wage growth makes more sense, he said.

Still, that analysis assumes that productivity gains translate into higher wages—and there are reasons to think that might be less true now than it has been in the past, as Zandi noted. Economists point to the long-term decline in worker bargaining power as part of the reason that employees’ paychecks are not rising right now. The share of employed workers who are members of a union has fallen in half since the 1980s. States have eroded labor standards and hampered collective bargaining. As a result, it is harder for workers to demand higher paychecks, year after year after year.