The six years preceding the 1952 Revolution are known as the sexenio. During this period, members of the Conservative Party tried to stem the growth of the left, but they ultimately failed because they could not halt the economic decline and control the growing social unrest. Enrique Hertzog Garaizabal (1947-49), who was elected president in 1947 after the interim rule of a provisional junta, formed a coalition cabinet that included not only the concordancia but also the PIR. He hoped to retain the backing of the Conservative Party forces by not increasing taxes, but he tried also to gain labor support, relying on the PIR to mobilize the workers.

The labor sector did not cooperate with the government, however, and the PIR became discredited because of its alliance with the conservative forces. In 1946 the workers endorsed the Thesis of Pulacayo, in which the miners called for permanent revolution and violent armed struggle for the working class. As the labor sector became more radical, the government resorted more and more to oppression, and confrontations increased. The dismissal of 7,000 miners and the brutal suppression of yet another uprising in Catavi in 1949 made any cooperation between the government and the workers impossible.

The MNR emerged as the dominant opposition group. Although most of its leaders, including Paz Estenssoro, were in exile in Argentina, the party continued to be represented in the Chamber of Deputies and the Senate. During the sexenio, the party, despite its predominantly middle-class background, repeatedly took the side of the workers and adopted their ideology. The MNR also came to support the defense of Indian rights, as violence in the countryside increased when the promises given at the National Indigenous Congress were not fulfilled.

The MNR's attempts to gain power during the sexenio were unsuccessful. Its 1949 coup attempt failed, although with the support of the workers and some military officers it succeeded in gaining control of most major cities except La Paz. The MNR's attempt to gain power by legal means in 1951 also failed. In the presidential election of May 1951, the MNR's Paz Estenssoro, who remained in exile in Argentina, ran for president and Siles Zuazo ran for vice president, both on a platform of nationalization and land reform. With the support of the POR and the newly formed Bolivian Communist Party (Partido Comunista de Bolivia -- PCB), the MNR won with a clear plurality. The outgoing president, however, persuaded the military to step in and prevent the MNR from taking power. Mamerto Urriolagoitia Harriague (1949-51), who had succeeded the ailing Hertzog in 1949, backed a military junta under General Hugo Ballivián Rojas (1951-52). Under Ballivián, the government made a last futile attempt to suppress the growing unrest throughout the country.

By 1952 the Bolivian economy had deteriorated even further. The governments of the sexenio had been reluctant to increase taxes for the upper class and to reduce social spending, resulting in high inflation. The tin industry had stagnated since the Great Depression, despite short revivals during World War II. Ore content had declined, and the richer veins were depleted, increasing tin production costs; at the same time, tin prices on the international market fell. A disagreement with the United States over tin prices halted exports temporarily and caused a decline in income that further hurt the economy. The agricultural sector lacked capital, and food imports had increased, reaching 19 percent of total imports in 1950. Land was unequally distributed--92 percent of the cultivable land was held by estates of 1,000 hectares or more.

The social unrest that resulted from this economic decline increased during the last weeks before the 1952 Revolution, when a hunger march through La Paz attracted most sectors of society. The military was severely demoralized, and the high command called unsuccessfully for unity in the armed forces; many officers assigned themselves abroad, charged each other with coup attempts, or deserted.

By the beginning of 1952, the MNR again tried to gain power by force, plotting with General Antonio Seleme, the junta member in control of internal administration and the National Police (Policía Nacional). On April 9, the MNR launched the rebellion in La Paz by seizing arsenals and distributing arms to civilians. Armed miners marched on La Paz and blocked troops on their way to reinforce the city. After three days of fighting, the desertion of Seleme, and the loss of 600 lives, the army completely surrendered; Paz Estenssoro assumed the presidency on April 16, 1952.

Data as of December 1989