Our estimates suggest that teacher collective bargaining worsens the future labor market outcomes of students: living in a state that has a duty-to-bargain law for all 12 grade-school years reduces earnings by $800 (or 2%) per year and decreases hours worked by 0.50 hours per week. The earnings estimate indicates that teacher collective bargaining reduces earnings by $199.6 billion in the US annually. We also find evidence of lower employment rates, which is driven by lower labor force participation, as well as reductions in the skill levels of the occupations into which workers sort. The effects are driven by men and nonwhites, who experience larger relative declines in long-run outcomes.
That is from a new paper by Michael Lovenheim and Alexander Willen, via Noah Smith.