Unions have advanced considerably in size and reach since the concept’s widespread inception at the turn of the 19th century. Born as a reflex to the harsh conditions forced on early industrial workers, the notion of a union of mutually protected employees has continued to attract individuals from numerous professions.

Today, around 11% of the working population are union members, and unions have expanded far beyond the industrial sector: teachers, hospitality employees, retail workers, and more have organized massive unions, each with millions of members. Below, you’ll find a bit more information about the organizations that comprise America’s five largest unions.

United Food and Commercial Workers

The UFCW represents around 1.2 million workers across the United States and Canada. It was founded in 1979 and primarily supports employees of the food, textile, healthcare, and agriculture industries. Charitable endeavors are also a focus of the UFCW; the group was integral in establishing 2010’s “Feeding the Hungry” campaign, which helped provide 20 million servings of protein to children left hungry during the Great Recession.

International Brotherhood of Teamsters

Over a century old, the IBT was founded in 1903, the result of a merger of several smaller cart drivers’ unions. Today, the IBT boasts a diverse coalition of 1.4 million blue and white collar professionals, from private and public sectors. The group’s stated objective is to “organize and educate workers toward a higher standard of living.”

American Federation of State, County and Medical Employees

America’s largest union of public service employees, the AFSCME currently holds about 1.6 million members, including nurses, corrections officers, child care providers, EMTs and more. The AFSCME advocates for the social and economic rights of its members through political activism and supporting relevant legislation.

Service Employees’ International Union

The SEIU was formed in 1921, and it was then called the Business Service Employees’ Union. Representing 1.9 million employees in healthcare, real estate and public service, their primary concern is preserving workers’ rights and ensuring stability in wake of economic struggles.

National Education Association

The NEA is the largest labor union in the United States, representing over 3.2 million teachers counselors, and other scholastic staff employed in public education and universities. Their network consists of more than 14,000 local affiliations in the US alone, a far-reaching infrastructure which enables them to advance their mission to facilitate education for children across the globe.