The American Federation of Labor and Congress of Industrial Organizations (AFL-CIO) is the largest federation of labor unions in the United States, formed in 1955 through the merger of the American Federation of Labor (AFL), established in 1886 by Samuel Gompers to represent skilled craftsmen, and the Congress of Industrial Organizations (CIO), founded in 1935 under John L. Lewis to organize industrial workers across mass-production industries like steel, auto, and rubber. The AFL initially focused on craft unions and was often conservative and exclusionary toward women, minorities, immigrants, and unskilled workers, while the CIO was more inclusive and aggressive in pushing for workers' rights, leading to tensions that eventually resolved in the merger. This union brought together diverse sectors of the labor movement, adapting to economic changes from the industrial era to the rise of the service and gig economies. As a voluntary federation, the AFL-CIO has limited authority over its member unions but coordinates efforts to advocate for higher pay, better working conditions, and social equity. It currently includes 57 to 61 national and international unions, representing approximately 12.5 to 15 million active and retired workers across various industries. The organization engages in substantial political spending and activism, supporting progressive and pro-labor policies, lobbying Congress, and promoting economic development through affiliated entities like the Working for America Institute. It also maintains an active international presence, affiliated with the International Trade Union Confederation since 2006, and historically opposed communist unions during the Cold War in regions like Latin America and Europe. The AFL-CIO's mission emphasizes liberty, justice, and solidarity for working families, dedicating itself to vanquishing oppression and advancing democracy. It has evolved with technological and economic shifts, fostering an inclusive movement that addresses contemporary challenges such as the gig economy and worker protections. Leadership transitions, such as the death of President Richard Trumka in 2021, highlight its ongoing role in national labor discourse, including calls for legislation like the Protecting the Right to Organize Act.