There are several categories of strikes. In the United States, the most prevalent is the wage and working-conditions strike. Here, labor unions negotiate for better wages and an improved quality of life. Strikes related to disagreements over contract terms are less common. Occasionally workers strike to force an employer to recognize a union that will represent its employees. Closely related to the strike is the lockout, an employer imposed closing used to bring economic pressure on disenchanted workers.

The industrial and political characteristics of the United States provide fertile ground for labor strife. Favorable laws guarantee the right to strike for most non-public employees, although there are restrictions against strikes that may significantly affect the life of the nation. While firms may hire replacement workers or scab labor, this is commonly a last resort because it results in strained relations between replaced workers and the employer. Other types of labor disturbances, such as slowdowns, sitdowns and sympathy strikes, are generally illegal.

While strikes by public employees are forbidden, they have become increasingly common. A milestone in this area was the 1970 strike by US postal workers. The strike was resolved to the benefit of the workers. In the early 1980s, however, President Ronald Reagan squashed a national air-traffic controllers’ strike, permanently banning strikers from work in the traffic-control industry.

By nature, strikes by skilled workers are most effective. This is because replacements are not easily found. Thus, the primary successes of the labor movement have been realized among professional unions such as teachers’ unions. These strikes are usually settled quickly with strikers demands at least partially met. Interestingly, all of the four major professional sports have seen lockouts or strikes in the past two decades. The strikes normally oppose efforts by team owners to restrict player salary escalation by imposing caps or taxes. These strikes have had a significant impact on attendance and fan interest, but salary growth has not slowed.

The most prominent trend in industrial labor strife is the opposition to part-time and subcontracted labor. US labor laws require that most fulltime, permanent employees be covered by extensive benefit packages, including healthcare, pension and disability insurance. To control rising labor costs, many firms have sought to outsource tasks or hire temporary workers. A 1997 strike by UPS package deliverers, 1998 strikes by transit workers in Philadelphia, PA and automobile strikes across the country have brought these issues to the forefront.

Large work stoppages have declined from pre1980 levels. According to the Bureau of Labor Statistics, the US averaged over 300 stoppages involving more than 1,000 employees per year from 1947–79. Since 1980, the average has declined to just fiftyeight such work stoppages per year.

The term “strike” has additional applications. Hunger strikes and student strikes have been undertaken to oppose political undertakings such as the Vietnam War or investment in South Africa under Apartheid, as well as socio-economic conditions such as the plight of the inner cities.