Formed in 1903 by the merger of The Team Drivers International Union and The Teamsters National Union, the union now represents a diverse membership of blue-collar and professional workers in both the public and private sectors. The union has approximately 1.3 million members as of 2020.

The Teamsters are known as the champion of freight drivers and warehouse workers, but have organized workers in virtually every occupation imaginable, both professional and non-professional, private sector and public sector.