On November 9, 1935, the Congress of Industrial Organizations (CIO) was founded. In the new era of industrial unions, workers were organized by industry rather than by skill (as in the craft unions of old). Over time, the membership of the American Federation of Labor (AFL)--whose existence preceded that of the CIO--came to be dominated by industrial unions. In 1955, the two federations merged, forming the AFL-CIO, which exists to this day.