There are various ways to classify unions, such as public unions of government workers, private unions for business-sector workers, professional unions for white-collar workers and craft unions for blue-collar workers. There are also business unions to advance workers' benefits and political unions to deal with the government.
Most American labor unions are business unions that support the capitalist system and work to enhance members' wages, benefits and working conditions. Many American labors unions also do the work political unions do, such as lobbying for and supporting political parties and individual candidates.
Most unionized workers in America are members of industrial unions, such as the United Auto Workers, a private union. Historically, industrial unions represented workers from related fields, but have been diversifying their members' occupations in recent years. For example, in the 1990s, the UAW added the National Writers Union, Graphics Artists Guild and some university employees.
Craft unions traditionally represent highly skilled laborers in closely related industries. Craft unions represent trade workers in the construction industry such as electricians, carpenters and plumbers. These unions help place workers in jobs and also perform collective bargaining on wages and benefits.
Professional unions represent highly skilled workers with degrees or special licenses. The National Education Association of teachers, staff and other public school employees is an example of a professional union. The NEA is also a public union.