Argentina's indigenous population before European contact consisted of numerous distinct groups adapted to radically different environments. The Diaguita and Calchaquí peoples inhabited the northwestern valleys and had developed irrigation agriculture and metallurgy before Inca expansion reached them in the mid-15th century. The Guaraní occupied the northeastern subtropical forests along the Paraná River. The Mapuche controlled vast territories in Patagonia and the Andean foothills. The Tehuelche and Selk'nam were nomadic hunter-gatherers in the southern steppes and Tierra del Fuego. The Comechingones lived in the Córdoba hills. The Wichí, Toba, and Mocoví peoples inhabited the Gran Chaco. Unlike Mexico or Peru, the territory that became Argentina had no centralized empire and no urban centers comparable to Tenochtitlan or Cuzco. Population density remained low, estimated at 300,000 to 500,000 across the entire area at contact.
Spanish exploration of the Río de la Plata estuary began in 1516 when Juan Díaz de Solís led an expedition that ended with his death at indigenous hands. Sebastián Cabot explored the Paraná River in 1526-1530. Pedro de Mendoza founded the first Buenos Aires settlement in February 1536 with approximately 1,600 men. Starvation and Querandi attacks forced abandonment in 1541, and survivors relocated north to Asunción in present-day Paraguay. Juan de Garay refounded Buenos Aires on June 11, 1580 with sixty Spanish settlers and cattle brought downriver from Asunción. This second founding established the permanent European presence. Throughout the colonial period, Buenos Aires remained subordinate to the Viceroyalty of Peru, administered first from Lima and then from Charcas. The city functioned primarily as a smuggling port since Spanish mercantilist policy prohibited direct trade with Spain, requiring all commerce to route through Panama.
The interior developed along entirely different lines. Santiago del Estero, founded in 1553, became the oldest continuously inhabited city. Tucumán (1565), Córdoba (1573), Salta (1582), and Jujuy (1593) formed an agricultural corridor connected to the mining economy of Potosí in Upper Peru. Córdoba developed as an educational center when the Jesuits established their college in 1610, which became Argentina's first university in 1622. The Jesuit missions in Misiones province gathered Guaraní populations into reduction settlements beginning in 1609. San Ignacio Miní, founded in 1632, eventually housed 3,000 Guaraní. At their peak around 1730, thirty Jesuit missions in the Río de la Plata region contained approximately 140,000 Guaraní organized in agricultural communes that produced yerba mate, cotton, and cattle. King Charles III expelled the Jesuits from all Spanish territories in 1767, and the mission system collapsed within a generation.
The Bourbon Reforms attempted to tighten colonial administration and increase revenue extraction. Spain created the Viceroyalty of the Río de la Plata on August 1, 1776, separating the region from Peru and making Buenos Aires the administrative capital governing present-day Argentina, Uruguay, Paraguay, and Bolivia. The new viceroyalty contained approximately 400,000 inhabitants, with Buenos Aires holding only about 24,000. The 1778 decree allowing direct trade with Spain transformed Buenos Aires from a marginal port into a major commercial center. British invasions in 1806 and 1807 saw redcoat forces briefly occupy Buenos Aires before local militias expelled them without help from Spain. These victories generated political confidence among criollo elites and demonstrated Spain's military weakness.
Napoleon's invasion of Spain in 1808 and the subsequent imprisonment of King Ferdinand VII created the legitimacy crisis that precipitated independence movements. Buenos Aires criollos deposed Viceroy Baltasar Hidalgo de Cisneros on May 25, 1810 and established the Primera Junta, the first autonomous government. This May Revolution did not initially declare independence but claimed to govern in Ferdinand's name. The junta sent military expeditions to suppress royalist resistance in the interior. Manuel Belgrano led the Army of the North to Paraguay and then to Upper Peru. José de San Martín arrived in Buenos Aires in 1812 after military service in Spain and took command of the Army of the North in 1814. Political fragmentation accelerated as regional caudillos rejected Buenos Aires's centralizing ambitions.
The Congress of Tucumán declared independence from Spain on July 9, 1816 in San Miguel de Tucumán, with representatives from most provinces except those occupied by royalists. The declaration named the country the United Provinces of South America. San Martín executed his Andean crossing in January 1817, leading 5,200 men across six mountain passes, the main column crossing the Uspallata Pass at elevations exceeding 3,600 meters. His Army of the Andes defeated royalist forces at Chacabuco on February 12, 1817, liberating Chile. After securing Chilean independence, San Martín sailed north with a Chilean squadron and landed near Lima in September 1820. He declared Peruvian independence on July 28, 1821 but withdrew after his July 1822 Guayaquil meeting with Simón Bolívar, whose forces ultimately completed Peru's liberation.
The post-independence decades dissolved into civil war between Unitarios, who favored a centralized government based in Buenos Aires, and Federales, who demanded provincial autonomy. These conflicts were ideological, economic, and regional. Buenos Aires controlled customs revenue from the port but refused to share it with interior provinces. Caudillos commanded personal armies and frequently switched allegiances. Juan Manuel de Rosas, a wealthy estanciero from Buenos Aires province, became governor in 1829 and again from 1835 to 1852, exercising dictatorial power and controlling foreign policy for the entire confederation. Rosas enforced Federalist orthodoxy through la Mazorca, a paramilitary group that terrorized Unitario opponents. He blockaded Uruguay, fought the British and French navies simultaneously in 1845-1850, and maintained the confederation through violence and patronage networks. Justo José de Urquiza, the Federalist governor of Entre Ríos, turned against Rosas and defeated him at the Battle of Caseros on February 3, 1852 with Brazilian and Uruguayan support.
The 1853 Constitution established a federal republic modeled partly on the United States Constitution. Buenos Aires province seceded and remained separate until 1859, rejoining after military defeat but maintaining substantial autonomy. The constitution remained in effect with modifications until the 1949 Peronist constitution and was restored in 1956, then substantially reformed in 1994. Buenos Aires became the federal capital in 1880 after federalization ended its status as provincial capital. The city of La Plata was purpose-built as the new capital of Buenos Aires province, founded in 1882.
The Conquest of the Desert campaigns between 1878 and 1885, led by General Julio Argentino Roca, militarily incorporated Patagonia and the Pampas into effective Argentine control. Roca commanded 6,000 troops equipped with Remington rifles against Mapuche, Ranquel, and Tehuelche peoples. The 1879 campaign alone captured or killed an estimated 14,000 indigenous people and seized approximately 15,000 square miles of territory. Indigenous survivors were distributed as forced laborers to estancias or concentrated in reservations. The campaign opened 25 million acres for European settlement and cattle ranching. Roca served as president from 1880 to 1886 and again from 1898 to 1904, representing the oligarchic Generation of 1880 that consolidated national institutions and promoted massive European immigration.
Argentina received the second-largest European immigration flow in the Americas after the United States. Between 1870 and 1930, approximately 6.6 million immigrants arrived, though many returned after seasonal agricultural work. The 1869 census recorded a population of 1.8 million. The 1914 census showed 7.9 million, with 30 percent foreign-born. Italians comprised roughly 45 percent of immigrants, Spaniards 32 percent, with significant numbers from France, Poland, Russia, the Ottoman Empire, and Germany. Buenos Aires grew from 180,000 residents in 1869 to 1.5 million in 1914. This demographic transformation created the only Latin American country where the indigenous and mestizo population became a small minority replaced by European immigrants and their descendants. The immigration was unequal across regions. Buenos Aires, Santa Fe, Córdoba, and Mendoza received the vast majority. Patagonia received Welsh settlers in Chubut beginning in 1865. The northwest and northeast remained predominantly mestizo and indigenous.
The export economy boomed between 1880 and 1930 based on grain and cattle. Argentina became the world's leading exporter of beef, corn, and linseed, and the third-largest wheat exporter. Refrigerated shipping, first used in 1876, enabled frozen beef exports to Europe. British capital financed railroads, ports, and meatpacking plants. By 1914, Argentina had 21,000 miles of railroad track, eighth-most in the world. British investment in Argentina totaled approximately £480 million in 1913, more than in any other Latin American country. Per capita income in 1913 placed Argentina among the ten wealthiest nations. This prosperity concentrated in the hands of a landowning oligarchy who controlled politics through electoral fraud. Universal male suffrage existed on paper but local bosses delivered votes through clientelism and intimidation.
The Radical Civic Union, founded in 1891, challenged the oligarchic order and demanded clean elections. The Sáenz Peña Law of 1912 established secret, mandatory voting for all native-born males over eighteen. Hipólito Yrigoyen, the Radical leader, won the presidency in 1916 with middle-class and immigrant support. His administration coincided with World War I, during which Argentina remained neutral and profited by selling to both sides. The Semana Trágica in January 1919 saw police and right-wing militias kill between 700 and several thousand workers and Jewish residents during labor strikes in Buenos Aires. Estimates vary widely because authorities never published casualty figures. The Patagonia Rebelde of 1920-1921 ended with army troops executing between 1,500 and 3,000 striking rural workers and anarchist organizers. Yrigoyen returned to the presidency in 1928 but was overthrown by General José Félix Uriburu's military coup on September 6, 1930, the first of many successful coups.
The period between 1930 and 1943, known as the Infamous Decade, restored the conservative oligarchy through systematic electoral fraud. The Great Depression destroyed agricultural export markets. Unemployment reached 30 percent in 1932. Britain reduced Argentine beef imports to protect dominion producers. The Roca-Runciman Treaty of 1933 granted Britain preferential trade terms and control over Argentine transportation infrastructure in exchange for maintaining reduced beef quotas. Import-substitution industrialization began during this period as currency devaluation made foreign manufactured goods expensive. Manufacturing employment grew from 480,000 in 1935 to 830,000 in 1943. Internal migration brought workers from the interior provinces to Buenos Aires and Rosario industrial suburbs.
Colonel Juan Domingo Perón emerged from the June 4, 1943 military coup that ended the Infamous Decade. Perón became secretary of labor and welfare in 1943 and used the position to build a mass working-class base by enforcing labor laws, raising wages, and expanding union rights. When rival officers arrested him in October 1945, union-organized demonstrations on October 17 forced his release. He married radio actress Eva Duarte on October 22, 1945. Perón won the February 1946 presidential election with 56 percent of the vote. His government nationalized the British-owned railroads in 1948 for £150 million, purchased the American-owned telephone company, and created state enterprises in steel, energy, and shipping. The Five-Year Plan redistributed income through wage increases, price controls, and subsidized housing. Real wages rose approximately 40 percent between 1946 and 1949. Eva Perón, known as Evita, operated the Eva Perón Foundation, which distributed food, clothing, and money directly to the poor, bypassing traditional charities. The foundation spent an estimated $200 million annually at its peak, funded by mandatory union and business contributions.
The 1949 constitutional reform allowed presidential reelection, expanded workers' rights, and asserted state ownership of natural resources. Perón won reelection in 1951 with 62 percent. Eva Perón died of cervical cancer on July 26, 1952 at age thirty-three. Her death eliminated Perón's most effective communicator and removed a personality cult that had sustained working-class support even as economic conditions deteriorated. Agricultural production stagnated because price controls and export taxes reduced farm profitability. Inflation reached 40 percent in 1951. Foreign exchange shortages forced austerity. Perón's conflict with the Catholic Church escalated in 1954 when he legalized divorce and removed religious education from schools. The navy bombed the Plaza de Mayo on June 16, 1955, killing 364 civilians in an attempted coup. General Eduardo Lonardi successfully overthrew Perón on September 16, 1955. Perón fled to Paraguay and eventually to Spain.
The Revolución Libertadora military government proscribed Peronism, banned the party, and prohibited mention of Perón or Eva Perón's names. The Peronist labor movement went underground. Every election between 1955 and 1973 excluded Peronist candidates, creating structural illegitimacy. Arturo Frondizi won the 1958 presidential election with Peronist support after promising to legalize the movement. He governed under constant military pressure and was overthrown in 1962. Arturo Illia won the 1963 election but was deposed in 1966 by General Juan Carlos Onganía, who suspended Congress and political parties. Economic liberalization under Onganía's economy minister Adalbert Krieger Vasena provoked massive strikes. Police killed approximately fifteen protesters in Córdoba during the Cordobazo uprising of May 29, 1969. Guerrilla groups emerged from the radicalized left: the Montoneros, who identified as Peronist, and the People's Revolutionary Army (ERP), a Trotskyist organization. The Montoneros kidnapped and executed former president Pedro Aramburu in May 1970.
General Alejandro Lanusse allowed elections in 1973 after negotiating with Perón in Madrid. Peronist candidate Héctor Cámpora won in March 1973 and immediately freed imprisoned guerrillas. Perón returned on June 20, 1973 to a massive reception at Ezeiza Airport that descended into gunfire between left and right-wing Peronist factions. Conservative union leaders and armed groups killed at least thirteen and wounded 365 in what became known as the Ezeiza Massacre. Cámpora resigned in July, and Perón won election in September 1973 with 62 percent, with his third wife Isabel Perón as vice president. Perón died on July 1, 1974. Isabel Perón became the Western Hemisphere's first female head of state but lacked political skill and relied on José López Rega, her minister of social welfare, who organized the Argentine Anticommunist Alliance (Triple A), a death squad that killed an estimated 1,500 left-wing activists, intellectuals, and politicians between 1974 and 1976.
The armed forces overthrew Isabel Perón on March 24, 1976 and installed General Jorge Rafael Videla as president. The military junta launched the Process of National Reorganization, known as the Proceso, which conducted systematic state terrorism against suspected subversives. The Dirty War lasted from 1976 to 1983. The military operated approximately 340 clandestine detention centers where prisoners were tortured before execution. The Navy Mechanics School (ESMA) in Buenos Aires held an estimated 5,000 prisoners during the dictatorship. Prisoners were commonly drugged and thrown alive from aircraft into the Atlantic Ocean during death flights. The military disappeared an estimated 30,000 people, though exact numbers remain disputed because the junta destroyed records. The Mothers of the Plaza de Mayo, founded in April 1977, marched every Thursday afternoon demanding information about their disappeared children. Economy Minister José Martínez de Hoz implemented radical free-market policies, opening imports, deregulating finance, and privatizing state companies. External debt increased from $8 billion in 1976 to $45 billion in 1983. Industrial employment fell by one-third.