The workers' movement emerged by the end of World War I. From that time, the labor movement was greatly influenced by episodes of violent confrontation. The most critical of these occurred during the first massive industrial action, aimed at the United Fruit Santa Marta complex in 1928 when railroad, banana, and field workers went on strike to force changes in wages, hours, and non-wage compensation. The human toll was 1,000 dead. The aftermath of this tragedy diminished the dominance of the Conservative Party and contributed to the Liberal Party winning the presidency. The incoming government had a more open and pragmatic stance toward labor activities and pressed for important labor reforms, which helped in union expansion nation-wide. During this period, there was a greater participation of labor in national politics, mainly through the Liberal Party. The Confederation of Colombian Workers (Confederacion de Trabajadores Colombianos, CTC) was created in 1935, and represented the first successful attempt at uniting smaller unions from various professions into a collective organization. Later, Cold War ideological confrontation led to fears by more conservative elements that the CTC was too left-wing; thus in 1946 the Catholic Church established the Union of Colombian Workers (Union de Trabajadores Colombianos, UTC), which gained important support from the more moderate unions.
A second labor confrontation occurred in 1947 during a strike by port workers on the Magdalena River, which also ended in the loss of lives. During the "Violencia" (1948-66), organized labor became increasingly demoralized and weakened. After 1960, however, 2 more labor federations emerged: the Trade Union Confederation of Colombian Workers (Confederacion Sindical de Trabajadores Colombianos, or CSTC) and the General Confederation of Workers (Confederacion General de Trabajadores, or CGT). The former was aligned with the communists and the latter with the tiny Social Christian party. However, although the percentage of workers enrolled in unions more than doubled from 1959 to 1965, union membership was still a very low 13.4 percent.
Later on, in September 1986, an important group of independent unions and those affiliated with the CSTC joined forces to create the United Workers Central Organization (Central Unitaria de Trabajadores, or CUT). The CUT represented 70 to 75 percent of the organized workforce, and emerged as a major voice against organized violence. This organization proved to be less timid in terms of industrial action, and by the late 1980s the labor movement appeared to play a greater role in representing workers' social and political rights. Working conditions and wages are governed by the Labor Code of 1950 and some additional laws. The work week is 48 hours, except in agriculture. Fringe benefits include annual vacations and sick benefits. Employees are eligible for a retirement pension after 20 years of service. Social security is compulsory with the employer paying half the cost and the employee and the government paying a quarter each.
The total workforce of Colombia reached 18 million by 1999, with a record 20 percent unemployment level due to the recession, which has affected living standards and poverty levels, especially in the countryside.