Labor unions represent workers in particular industries, trades or sectors. They organize their members to negotiate improved wages, benefits and working conditions. Although union membership in the United States peaked in the mid-20th century and has declined since then, various types of labor unions remain an influential force in American business and politics.

Craft Unions

Craft unions have their roots in the guilds of medieval Europe. In occupations such as bakers and blacksmiths, apprentices learned their trades from masters through the guilds, which regulated production by setting prices and limiting wages and employment. Modern craft unions continue to represent workers in specific occupations, especially skilled trades. Craft unions in the United States include the International Brotherhood of Electrical Workers, the United Auto Workers, and the International Association of Machinists.

Industrial Unions

In contrast to craft unions, which represent members in specific trades, such as machinists, carpenters and electrical workers, industrial unions represent workers in industrial sectors, such as transportation or food service. One of the largest industrial unions in the United States is the International Brotherhood of Teamsters. Initially a union that represented workers in long-haul trucking, the Teamsters' membership comprises workers in a variety of industrial jobs, including trucking, warehouse and construction. Other industrial unions in the United States include the United Food and Commercial Workers, consisting of workers in restaurants and other food service industries, and the Organization of Chemical and Atomic Workers, which represents workers in chemical industries and nuclear power plants.

Public Sector Unions

Public sector unions are similar to industrial unions in that they represent workers, regardless of occupation, in a particular sector or industry. In this case, that sector is government agencies, including public schools. Two of the largest labor unions in the United States are public sector unions: the National Education Association, representing public school employees, and the American Federation of State, County and Municipal Employees, better known as AFSCME, which represents employees of state, county and city governments. Union membership in the United States is much higher among public sector employees than among private sector workers.

Advantages and Disadvantages of Labor Unions

Labor unions provide a sense of security for workers in various industries because they create better job protections for employees. They do this by allowing workers to bargain collectively with business owners for better compensation, safer working conditions, discrimination protections and more reasonable working hours. Also, many unions bargain for things like improved health coverage, more paid vacation days, better retirement benefits, higher unemployment compensation and other perks for employees.

Unfortunately, labor unions may charge excessive membership dues of employees and pressure employees into joining them. Unions may also force employees into a strike during bargaining sessions with businesses, effectively depriving the employees of their wages. In addition, when forced to pay higher wages and benefits to their employees, businesses may become less competitive in the marketplace. Because of this, many businesses tend to shy away from supporting unions and employing union members because of financial concerns about wages and employee contracts.