The Argentine population, which represented 0.13% of the world population in 1869, would go on to represent 0.55% in 1930, a proportion in which, approximately, it would stabilize since then. The country was known at that time as the breadbasket of the world.
The prosperity of the economy fueled the growth of the middle class, the creation of modern political parties such as the Unión Cívica Radical (UCR) and the Socialist Party (PS), and a broad development of trade unions.
After more than two decades of political and social conflicts and serious acts of repression, the Sáenz Peña Law was enacted, establishing secret, compulsory and universal suffrage for male voters in 1912.
In the first presidential election with secret suffrage, the conservatives were overthrown by the radicals, assuming Hipólito Irigoyen (1916 – 1922 and 1928 – 1930) the presidency of the government. During his first government, the student movement known as the university reform began, which spread throughout Latin America.
Coups d’état and instability
In the international context of the Great Depression that followed the Black Thursday of 1929, the 6 of September of 1930 there was the first of a series of coups in Argentina who took power from the military to establish a de facto government, after to overthrow Hipólito Yrigoyen.
This coup began an era known as the Infamous Decade. From that decade on, the country promoted a process of import substitution that developed a large industrial sector. The Infamous Decade ended with the Revolution of ’43, when a group of nationalist officers, led by General Arturo Rawson, took power. Among the leaders of this military coup, General Juan Domingo Perón appeared. Despite international pressure, Argentina remained neutral during most of World War II, and joined the Allies on March 27, 1945, during the government of Edelmiro Julián Farrell..
Perón, who became an emblematic figure of Argentina, campaigned in the less favored working class, the “descamisados”, and promised the distribution of land, higher wages and the introduction of social security. He widely triumphed in the elections of February 24, 1946, with 56% of the votes. The first years of the Peronist regime benefited from popular enthusiasm, sustained by the president’s wife, Eva Duarte, to whom Péron entrusted the Ministry of Labor and Social Affairs. Thanks to her work, women’s suffrage was established in 1947 by recognizing the political rights of women. Overthrown by a military coup in September 1955, Perón took refuge in Paraguay, then in Spain. The Peronists, whose party had been banned, nevertheless remained quite popular.  In the general elections that took place in February 1958, Arturo Frondizi came to the presidency, with the support of the Peronists and the Communists, being overthrown by a new military coup in 1962.
In 1964 he was elected president Arturo Umberto Illia (UCRP), who also would be overthrown by a military coup in 1966 that would establish a dictatorial regime of permanent type known as Revolution Argentina (1966- 1973). These years were characterized by a growing military repression against popular struggles that reached episodes such as the Cordobazo.
In 1973 Peronism was again legalized and triumphed in the presidential elections. After the resignation of Héctor José Cámpora, Juan Domingo Perón assumed the presidency for the third time, but would die less than a year later. He was succeeded by his Vice President and third wife, María Estela Martínez de Perón, whose government was characterized by an accelerated deterioration of the internal situation, as a result of the 1973 oil crisis.
Last Argentine military dictatorship and return to democracy
The 24 of March of 1976 took place with the backing of the United States – a new military coup self – appointed Process of National Reorganization, in front of which the Army was General Jorge Rafael Videla. The military junta pronounced the dissolution of Congress, imposed martial law, and ruled by decree. A very harsh repression was then launched against the opposition movements and manifested itself in executions, the practice of torture and disappearances. In 1977, the Commission on Human Rights, in Geneva, accused the regime of 2,300 political assassinations, some 10,000 arrests and the disappearance of 20 to 30 thousand people, of which a large number were assassinated by the Military Junta and buried without a burial.
In 1978 there was a serious crisis with Chile over the limits of the Beagle Channel area (Beagle Conflict), which brought both countries to the brink of war. During the Process there was a significant increase in the national external debt and the financial system became speculative. Videla was replaced in the presidency, in March 1981, by Roberto Viola, dismissed, in December 1981, by the commander-in-chief of the army, General Leopoldo Galtieri.
In 1982, Galtieri ordered Argentine troops to invade the Falkland Islands, a dispute between Great Britain and Argentina since the former invaded in the 19th century, long claimed by Argentina. But Great Britain sent a military intervention force in the South Atlantic which, after three months, beat the Argentine army and regained possession of the islands. Galtieri, then discredited, was replaced by Major General Reinaldo Bignone. 
Raúl Alfonsín, the radical candidate, won the presidential election in October 1983, the first organized after 10 years, and in a very difficult economic context, characterized by an unprecedented foreign debt and inflation above 900 p. 100. The nation then resumed with democracy: the armed forces were reorganized; former military and political leaders were accused of human rights violations and sent to court.  The Alfonsín government launched, in 1985, a rigorous budget plan. The external debt was restructured and fiscal reforms were carried out (including a new currency).
However, inflation was not contained, and in May 1989, the Peronist candidate, Carlos Saúl Menem, was elected president. Carlos Menem assumed the presidency six months earlier than stipulated due to the high inflationary process that the country was suffering, which He forced Raúl Alfonsín to submit his resignation without completely completing the mandate. Menem sanctioned the Austral Convertibility Law in 1991, which stopped inflation and adopted a neoliberal economic policy., supported by a wave of privatizations, reduction of tariffs on imported products and deregulation of markets. These measures that contributed to significantly increase investment, exports and growth with stable prices.  However, they also opened a de-industrialization process due to the impossibility of competition from the weakened Argentine industry, these measures also made the economy more vulnerable to international crises, and increased unemployment, poverty and job insecurity.  In 1993, President Menem voted on a constitutional revision, which reduced the presidential term to 4 years and allowed him to propose himself as a candidate for his own succession. He was thus re-elected in the first round, on May 14, 1995. Carlos Menem obtained extraordinary powers from Congress in February 1996 in order to be able to promote the second state reform aimed at reducing public spending, increasing tax collection and renegotiating a loan with the IMF. The ultra-liberal reforms caused the discontent of the vast majority of Argentines, a country located in South America according to PHYSICSCAT.COM. The partial legislative elections that took place on October 26, 1997 They gave victory to the Alliance (Radical Civic Union and Solidarity Front for the Country), a party opposed to the justicialists in power. President Menem would not have more since then with an absolute majority in Congress.