After suffering a countercyclical decline in the prosperous 1920s, the American labor movement grew in fits and explosive starts during the Great Depression and had finally come of age by 1940. Initially, the sole major organizational vehicle organizing unionized workers in the nation was the American Federation of Labor (AFL), which, carrying on the legacy of Samuel Gompers, was reluctant to take steps that might instigate government counteraction, and which therefore failed to exploit completely the growing unrest of American workers. Some AFL leaders, such as John L. Lewis of the Miners, had more aggressive views to push unionization into industries it had not yet substantially occupied, but these individuals were the exception in the organization, not the norm. A shift was precipitated by an act of legislature, the National Industrial Recovery Act of 1932, whose clause 7a guaranteed workers a choice of union and compelled employers to deal with those unions. The clause unleashed a wave of unionization, both spontaneous and driven by the AFL. Membership in the AFL surged, but the organization's conservatism--its orientation toward skilled labor, in particular--left it ill-equipped to organize and harness the energy of the mass of relatively unskilled workers clamoring to join the movement. In light of this roadblock (which actually caused the AFL to lose members), John L. Lewis formed the Committee for Industrial Organization (CIO) of ten of the more aggressive AFL unions. Within a year of its inception, the member unions of the CIO were expelled from the AFL and stood in the CIO as a distinct organization, at that point newly unhampered it its aggressive and sometimes violent pursuit of membership from unskilled labor. The CIO's tactics were effective, so that, by the time the AFL and the CIO reconciled in 1940, total union membership had risen to 8.5 million, from barely 3 million in 1929.