Labor unions in transportation exist mainly in the public transportation sector; there are private sector unions as well, but these are not as widespread. One of the largest players in transportation is the Teamsters union, which mainly deals with trains and trucking. The largest transportation-specific union in the United States is the United Transportation Union, based in Ohio, and representing over 120,000 transportation employees, both retired and current.

The UTU is notable for its broad inclusion of all types of public transport, from buses and trolley lines to airplanes and railroads. It does not include ocean and river transportation employees; these fall under separate maritime unions, with the Seafarers International Union of North America being the largest. Both of these major transportation unions strive for fair rights and wages for their members, fair retirement and pension packages, and management responsibility for oversight and abuse.

Most public employee unions engage in political lobbying, and are required to release their donation data regularly.