Labor unions represent United States workers in many industries recognized under US labor law since the 1935 enactment of the National Labor Relations Act. Their activity today centers on collective bargaining over wages, benefits, and working conditions for their membership, and on representing their members in disputes with management over violations of contract provisions. Larger labor unions also typically engage in lobbying activities and electioneering at the state and federal level.

The American Federation of Labor and Congress of Industrial Organizations (AFL-CIO) is a national trade union center that is the largest federation of unions in the United States. It is made up of 60 national and international unions, together representing more than 12 million active and retired workers. The AFL-CIO engages in substantial political spending and activism, typically in support of progressive and pro-labor policies.