Transit workers employed on New York's Interborough Rapid Transit Company (IRT) began organizing a union in 1934; the effort soon spread to the other two private transit companies in the New York system, the Brooklyn-Manhattan Transit Co. (BMT) and the Independent Subway System (ISS, later IND), and the TWU was chartered in the same year. The union's early activists were mostly Irish immigrants who came to the United States after the Irish Rebellion of 1916. The men who led the TWU organizing campaign brought the radical legacy of Irish labor leaders James Connolly and James Larkin to the New York transit system.

The Irish leadership of the TWU first approached fraternal associations in the Irish community and the Catholic Church for support, with little success. They finally accepted the assistance of the Communist Party, which had targeted New York City's transit workers as one of several large industrial workforces it wanted to bring under its political influence. The Party provided funds and an office, printed leaflets and brought in volunteers who could distribute them without facing loss of their jobs. Most important, it provided talented organizers who brought the infant union to maturity. Maurice Forge, Austin Hogan, and Harry Sacher became full time TWU organizers on the Party payroll. Forge, a commercial artist, handled the TWU's publicity and developed the Transport Workers Bulletin, the union's newsletter. Harry Sacher, an attorney, handled the TWU's legal affairs. Hogan took charge of day to day organizing efforts. Douglas McMahon, a BMT worker, was also hired as a full time organizer. In 1935 Mike Quill, a Kerry native and former ticket agent who had led early organizing efforts among Irish transit workers, became the first president of the TWU. Quill's charisma and leadership abilities quickly made him a key player in both the labor and political arenas in New York. He led the union until his death in 1966.

Eventually affiliating with the fledgling Congress of Industrial Organizations (CIO), the TWU soon became the bargaining agent for all New York City transit systems, and branched out to form locals across the country. By the 1950s the union boasted a membership of more than 100,000. Quill broke sharply with the Communist Party in the late 1940s, drove the most prominent Communist sympathizers from positions in the union, and took the TWU into new fields of organizing. TWU locals were established among railroad and airlines workers, utility workers and taxi drivers, among other ventures. These initiatives were continued under the presidency of Matthew Guinan and his successors in the office, although the decline in railroad employment and economic setbacks in other sectors resulted in some losses of membership. With a strong anti-discrimination tradition, the TWU pioneered in the formation of integrated locals in the south, and participated actively in the Civil Rights movement.

The international union remained based, and its membership concentrated, in the New York area. New York Local 100 has remained the largest and most influential in the TWU. The history of Local 100 is bound up in the labor and municipal history of New York City, with the Local facing bitter opposition from several mayors, from private employers, and, in recent decades, from the Metropolitan Transportation Authority. In the years following World War II the Local worked to reinstate returning veterans to the jobs and seniority they held prior to their war service. It won the battle for the five day, forty hour week. By 1950 Local 100 had organized the transit workers on the municipal subway and bus systems as well as the employees of most of the private bus companies in the New York metropolitan region. TWU contracts provided for a closed shop, wage increases, paid vacations, and significant improvements in working conditions. After an intense struggle Local 100 also defeated the unsound IRT Pension Plan and negotiated the return to union control of all funds contributed to the plan by the transit workers.

The Local 100 Education Department offered films, lectures, and classes where members could learn the skills of union participation including negotiation and grievance procedures and parliamentary procedure. They could also pursue personal interests such as improving English language skills, American history, photography and other hobbies. The Sports Department organized activities such as bowling leagues, baseball, softball, and football teams. Union-sponsored leisure activities also included choral singing, classes for the wives and children of members and annual outings.

Sources:

Joshua Freeman, In Transit(New York, Oxford University Press, 1989).