The Largest Labor Unions in the US
Only about one in ten American workers carries a union card today, a share that sits near a record low. But the country's largest unions are anything but small. The biggest of them, the National Education Association, has close to 3 million members on its own. And the modern roster of giants looks very different from the steel-and-auto image a lot of people still picture when they think of organized labor. The largest unions in the United States today are dominated by teachers, nurses, and government employees, not factory workers.
America's Largest Unions, by the Numbers
At the top sits the National Education Association, with roughly 3 million members, which makes it not only the largest union in the country but one of the largest membership organizations of any kind. Behind it, the Service Employees International Union represents around 2 million healthcare, public-service, and property workers. The American Federation of Teachers has grown sharply in recent years and now counts roughly 1.7 million members, which puts two teacher unions in the top three.
Here are the largest, by the most recent membership figures available. A quick caveat: these numbers are union-reported and rounded, and the exact order shifts depending on whether retirees and Canadian members are counted. That mostly affects the United Steelworkers and the auto workers, so treat the ranking as close rather than exact.
| Rank | Union | Approx. members (2024-2025) |
|---|---|---|
| 1 | National Education Association (NEA) | ~3,000,000 |
| 2 | Service Employees International Union (SEIU) | ~2,000,000 |
| 3 | American Federation of Teachers (AFT) | ~1,700,000 |
| 4 | American Federation of State, County and Municipal Employees (AFSCME) | ~1,400,000 |
| 5 | International Brotherhood of Teamsters | ~1,300,000 |
| 6 | United Food and Commercial Workers (UFCW) | ~1,200,000 |
| 7 | United Steelworkers (USW) | ~850,000 |
| 8 | International Brotherhood of Electrical Workers (IBEW) | ~800,000 |
| 9 | Communications Workers of America (CWA) | ~700,000 |
| 10 | Laborers' International Union of North America (LIUNA) | ~500,000 |
Why Teachers and Government Workers Dominate
The list tilts heavily toward public-sector work for a simple reason: that is where unions still thrive. About a third of government workers belong to a union, compared with only around 6% of private-sector workers, according to the Bureau of Labor Statistics. Teachers, in particular, are heavily organized. The NEA and the AFT together represent close to 5 million educators and school staff, and AFSCME adds another 1.4 million state, county, and municipal employees on top of that. SEIU rounds out the picture with healthcare and public-service workers. Four of the five largest unions in the country draw most of their members from public payrolls.
The Shrinking Industrial Unions
The unions that built the 20th-century labor movement have had a much harder run. The United Auto Workers, the very symbol of postwar American manufacturing, now counts roughly 400,000 active members, down sharply from a late-1970s peak of around 1.5 million. The United Steelworkers, once focused on a single industry, has survived partly by broadening into healthcare, chemicals, and other sectors. The decline tracks the long shrinkage of American factory employment rather than any loss of nerve. In 2023, the UAW ran a high-profile "stand-up strike" against the three big Detroit automakers and won large raises, proof that a smaller union can still hit hard.
Union or Federation? The AFL-CIO, Explained
People often call the AFL-CIO the largest union in America. It is not a union at all. It is a federation, an umbrella group of roughly 60 separate unions that together represent close to 15 million workers. An individual worker joins the Teamsters or AFSCME or the NEA; that union may then affiliate with the AFL-CIO, which coordinates political advocacy and supports major organizing drives. The distinction matters for any ranking, because the federation's headline number double-counts members who already belong to the unions beneath it. In 2025, the SEIU rejoined the AFL-CIO after a 20-year absence, bringing its roughly 2 million members back into the fold and reuniting most of organized labor under one roof.
Where Organized Labor Stands Now
The big picture is a paradox. Union membership as a share of the workforce keeps drifting downward, near the lowest level on record, and yet the largest unions remain some of the most powerful organizations in American life. What has changed is their center of gravity. A century ago, the biggest unions were built around coal, steel, and the assembly line. Today they are built around the classroom, the hospital, and the government office. The question the old "labor versus management" framing misses is that, for the largest unions in the country now, the employer on the other side of the table is increasingly the public itself.
