Local 100 is a local (or chapter) of the Transport Workers Union of America, a union that represents transportation workers in bus and subway lines, and several airlines nationwide. The Local primarily represents 41,000 workers in the New York City public transportation system and at some private bus lines serving the New York City metropolitan area. In the City's subway lines, Local 100 represents virtually all employees including those who operate trains, maintain the trains and tracks, staff the token booths, clean platforms and subway cars, and service and repair mechanical equipment such as elevators and escalators.

Local 100 represents most of the men and women who drive and maintain public buses buses in New York City under the umbrellas of MaBSTOA in Manhattan and the Bronx, NYC Transit Surface Division in Brooklyn, and MTA Bus in Queens and the Bronx. We are also proud to represent workers at other private transportation firms. Among these are members at Liberaty Lines, providing commuter transportation in Westchester, Waterways, servicing New York Waterway's ferry passengers, First Transit, where our members schedule paratransit service, horse carriage drivers in Central Park and several other school bus companies.