American Federation of Labor - Congress of Industrial Organizations (AFL-CIO)
http://www.aflcio.org/

American Federation of Government Employees (AFGE)
http://www.afge.org/

American Federation of School Administrators (AFSA)
http://www.afsaadmin.org/

American Federation of State, County and Municipal Employees (AFSCME)
http://www.afscme.org/

American Federation of Teachers (AFT)
http://www.aft.org/

American Postal Workers Union (APWU)
http://www.apwu.org/

Association of Flight Attendants - CWA (AFACWA)
http://www.afacwa.org/

Bakery, Confectionary, Tobacco Workers and Grain Millers International Union (BCTGM)
http://www.bctgm.org/

Communications Workers of America (CWA)
http://www.cwa-union.org/

International Association of Machinists and Aerospace Workers (IAM)
http://www.goiam.org/

International Brotherhood of Electrical Workers (IBEW)
http://www.ibew.org/

International Union of Automobile, Aerospace & Agricultural Implement Workers of America (UAW)
http://www.uaw.org/

IUE-CWA, Industrial Division of the Communications Workers of America 
http://www.iue-cwa.org/

National Football League Players Association
https://www.nflplayers.com

Sheet Metal Workers International Association (SMWIA)
http://www.smwia.org/

Transportation · Communications International Union (TCU)
http://www.tcunion.org/

Union of Needletrades, Industrial and Textile Employees and
Hotel Employees and Restaurant Employees International Union (UNITEHERE!)
http://www.unitehere.org/

United Food and Commercial Workers International Union (UFCW)
http://www.ufcw.org/

United Mine Workers of America
http://www.umwa.org/

United Steelworkers (USW)
http://www.usw.org/

Workers United
http://www.seiu.org/division/workers-united/