Labor history

Teacher collective bargaining went from rare to nearly universal in 17 years — once states passed the law

Percent of public-school teachers covered by collective bargaining agreements, 1960–1977. The bordered cell marks the year each state's bargaining law took effect.

Source: Saltzman, Gregory M. (1981), The Growth of Teacher Bargaining and the Enactment of Teacher Bargaining Laws, PhD dissertation, University of Wisconsin–Madison. Values transcribed from the published reproduction; see methodology.