Whether a nurse, teacher, actor, farmer or pilot, workers across the United States join labor unions to help protect their interests, financial livelihoods and retirements. Since the labor unions exploded into America's job force in the late 19th century, government policy and business policy have been molded around the powerful lobbying of labor unions. The nation has many unions, some with just a few thousand members and others with millions.

Communications Workers of America

The Communications Workers of America is the largest labor union that represents workers within the field of telecommunications. Workers in broadcasting, publishing and journalism are among the many careers represented by the union. As of 2010, the union counts more than 700,000 workers as part of its family, including more than 500,000 who work in web-based careers.

Communications Workers of America 501 3rd St. NW Washington, DC 20001 202-434-1100 cwa-union.org

AFL-CIO

The AFL-CIO is a federation of 56 labor unions across the globe. Its unions represent teachers, firefighters, bakers and pilots, just to name a few. More than 11 million workers are protected by the AFL-CIO, as of 2010.

AFL-CIO 815 16th St. N.W. Washington, DC 20006 202-637-5000 aflcio.org

American Federation of State, County & Municipal Employees

The American Federation of State, County & Municipal Employees (AFSCME) takes care of more than 1 million workers involved in various vital service careers such as sanitation workers, nurses, correction officers and emergency medical technicians.

American Federation of State, County and Municipal Employees 1625 L St. N.W. Washington, DC 20036 202-429-1000 afscme.org

International Association of Machinists & Aerospace Workers

This large labor union represents a variety of industrial careers. More than 700,000 million members, as of 2010, have careers in woodworking and the aerospace, automotive and transportation industries.

The International Association of Machinists and Aerospace Workers 9000 Machinists Place Upper Marlboro, MD 20772 301-967-4500 goiam.org

International Brotherhood of Teamsters

The Teamsters has more than 1 million current members and also counts more than 500,000 retired members. The union represents more than 21 industrial careers and includes workers in the film industry, dairy workers, delivery workers of UPS and DHL, freight railroad workers and printers.

International Brotherhood of Teamsters 25 Louisiana Ave. N.W. Washington, DC 20001 202-624-6800 teamster.org

Service Employees International Union (SEIU)

This large union of service employees counts more than 2 million members as part of its family. The union represents a variety of service careers including building security personnel, nurses, lab technicians, home care workers and public school employees.

Service Employees International Union 1800 Massachusetts Ave. NW Washington, DC 20036 202-730-7000 seiu.org

Transport Workers Union of America

The Transport Workers Union represents a variety of workers within the transportation industry such as subway workers, airline workers, bus drivers and railroad workers as well as workers in casinos. The union counts more than 200,000 members from across 22 states, as of 2010.

Transport Workers Union of America 1700 Broadway, 2nd Floor New York, NY 10019 212-259-4900 twu.org

UAW International

The UAW International union represents more than 1 million total workers, both retired and current, as of 2010. Most of the members work in manufacturing jobs and build items including heavy trucks, household appliances, farm equipment, musical instruments and automobiles.

UAW International Solidarity House 8000 E. Jefferson Ave. Detroit, MI 48214 313-926-5000 uaw.org

UNITE HERE!

UNITE HERE! is a large labor union that represents workers in both Canada and the United States. The people within the union's scope of representation include casino employees, airport terminal workers, textile and clothing manufacturers, and laundry workers. The union counts more than 500,000 workers as part of its membership, as of 2010.

UNITE HERE Headquarters 275 7th Ave. New York, NY 10001 212-265-7000 unitehere.org

United Farm Workers

Founded in 1966 by the Cesar Chavez, famous for his support of farm worker rights, the United Farm Workers represents workers within the farming, agriculture and dairy sectors. With active membership in 10 states across the country, the UFW represents close to 30,000 workers each year, as of 2010.

United Farm Workers 29700 Woodford-Tehachapi Road Keene, CA 93531 661-823-6250 ufw.org