The United Mine Workers of America is a North American labor union best known for representing coal miners. Today, the Union also represents health care workers, truck drivers, manufacturing workers and public employees in the United States and Canada. Although its main focus has always been on workers and their rights, the UMW of today also advocates for better roads, schools, and universal health care. By 2014, coal mining had largely shifted to open pit mines in Wyoming, and there were only 60,000 active coal miners. The UMW was left with 35,000 members, of whom 20,000 were coal miners, chiefly in underground mines in Kentucky and West Virginia. However it was responsible for pensions and medical benefits for 40,000 retired miners, and for 50,000 spouses and dependents.

The nature and power of organized labor in the United States is the outcome of historical tensions among counter-acting forces involving workplace rights, wages, working hours, political expression, labor laws, and other working conditions. Organized unions and their umbrella labor federations such as the AFL–CIO and citywide federations have competed, evolved, merged, and split against a backdrop of changing values and priorities, and periodic federal government intervention.