July 5 1935 The National Labor Relations Act, was signed into law
The National Labor Relations Act of 1935 29 U.S.C. § 151169 (also known as the Wagner Act after NY Senator Robert F. Wagner[1]) is a foundational statute of US labor law which guarantees basic rights of private sector employees to organize into trade unions, engage in collective bargaining for better terms and conditions at work, and take collective action including strike if necessary. The act also created the National Labor Relations Board which conducts elections which, if voted in favor of representation, awards labor unions (also known as trade unions) with a requirement for the employer to engage in collective bargaining with this union. The Act does not apply to workers who are covered by the Railway Labor Act, agricultural employees, domestic employees, supervisors, federal, state or local government workers, independent contractors and some close relatives of individual employers.[2]
http://en.wikipedia.org/wiki/National_Labor_Relations_Act