June 16, 1933 - President Franklin D. Roosevelt signed the National Industrial Recovery Act. One of its provisions recognized the right of workers to organize and bargain collectively through unions. The legislation, though later found unconstitutional by the U.S. Supreme Court, helped spurred massive union organizing. Finally, in 1935, Congress passed the National Labor Relations Act, the foundation of today's labor law.
Charles Morris' book, The Blue Eagle at Work, is an insightful analysis of the NIRA and how it is still useful today. Read a review of his book at http://www.nathannewman.org/laborblog/archive/002541.shtml