What was the highest legislative achievement for unions in U.S. history as referred to in the text?

The Wagner Act, officially known as the National Labor Relations Act of 1935, is regarded as the highest legislative achievement for unions in U.S. history because it significantly enhanced the rights of workers to organize and engage in collective bargaining. This act established the National Labor Relations Board (NLRB), which oversees the administration of labor laws and ensures that employees can exercise their rights to form unions without facing discrimination or retaliation from employers. It also made it illegal for employers to engage in unfair labor practices that would inhibit the formation of unions. By solidifying the legal framework for labor rights, the Wagner Act laid the groundwork for the growth and influence of labor unions across the United States, helping to improve working conditions, wages, and job security for many workers.