Percentage of Wage and Salary Workers Who Are Union Members

Barely 7 percent of wage and salary workers belonged to a union in the early 1930s. Membership then roughly quadrupled in under fifteen years, as new labor law and wartime industry brought millions into unions, and peaked at about 28 percent in the mid-1950s.

The decline since has been long and steady rather than sharp: about a quarter of workers in the early 1970s, a sixth by 1990, and 10.3 percent in 2021. Leaving out government workers, whose unions have held up better, only 6.1 percent of private-sector workers now belong to one. The slider drops the early years, which makes the pace of the decline easier to read. The series is read from the book's own figure, so treat it as close to but not exactly the published percentages.