In the United States, individuals often come together to fight for a common cause. Throughout the country's history, perhaps no such groups have been more rewarded for their persistence than labor unions. Some specific industries that are well-known for their labor unions are teachers, miners, steelworkers, auto workers and actors. So, you must join the union if you're going to work in certain professions, right?
Actually, no, though you may be pressured to do so in certain states.
The National Labor Relations Act (NLRA) passed in 1938 granted employees the right to choose whether or not to take part in union activities. Despite the NLRA, unions in the 28 states without an additional right-to-work law can pressure employers to hire or fire employees that don't pay union dues [sources: Hunter, NRTW].
You're likely to be persuaded to join a labor union for its benefits. A union's Collective Bargaining Agreements (CBA) with employers often mean higher salaries, better benefits, and more job security for those who pay membership dues to the union [source: AFL-CIO]. However, one reason you might not want to join a union is that by doing so you lose your ability to negotiate your individual salary and benefits. Plus, if the union is on strike, your employer is free to replace you permanently in order to continue operating, which could mean lost wages for you and your family [source: Hunter].