The Short Answer: Anyone!Any worker can form or join a union at its most basic: a group of workers who take collective action to win material changes in their workplace. You don't need to work in a specialized industry, make a certain amount of money, or be a certain kind of worker.However, most union workers have the full protections of US law. The major piece of legislation protecting workers’ right to unionize is the National Labor Relations Act (NLRA), which was created to protect the US labor force.Although most workers are eligible, certain people are excluded from the NLRA's protections.The Long Answer: Conflicts of InterestThese employees cannot form legally-protected unions in any state, as their role makes it impossible to have a fair negotiation with their employers.Supervisors and ManagersEmployees who are tasked with managing other employees, or making major company decisions with their own independent judgement, cannot join unions. They are classified as part of the compa...