Chronology: Checkered history of the PRI's rule in Mexico

MEXICO CITY (Reuters) - Mexico’s Institutional Revolutionary Party, or PRI, is favorite to win the presidential election on Sunday, offering a new start for a party that until 2000 held a 71-year grip on government with a mix of populism, patronage, corruption and repression.

The following chronology marks important moments in the PRI’s history since it first appeared in the years following the Mexican Revolution in the early 20th century.

- March 4, 1929. Plutarco Elias Calles, who led the revolution in its final stages, founds the National Revolutionary Party (PNR), a predecessor of the PRI.

- March 18, 1938. Leftist President Lazaro Cardenas (1934-1940) nationalizes the oil industry and creates Pemex, a state-run monopoly to this day.

- March 30, 1938. The PNR changes its name to the Mexican Revolutionary Party (PRM).

- August 21, 1944. President Manuel Avila Camacho enacts a bill outlawing illiteracy, a key moment in Mexico’s modernization that led to major improvements in education.

- January 18, 1946. The PRM becomes the PRI, marking an end to military presidents.

- March 1947. President Miguel Aleman creates the Federal Security Directorate. Officially the national intelligence agency, in reality it served as a tool of repression.

- August 4, 1964. President Adolfo Lopez Mateos refuses to break ties with Fidel Castro’s Cuba, taking an independent posture toward the United States that would last decades.

- October 2, 1968. After student protests under President Gustavo Diaz Ordaz, the army opens fire on demonstrators in Mexico City’s Tlatelolco district, killing dozens just days before the capital hosted the Olympic Games.

- June 10, 1971. Luis Echeverria is president during the so-called Corpus Christi massacre in which more protesters are shot dead, marking the beginning of a “dirty war” against dissenters.

- February 18, 1982. After profligate spending by President Jose Lopez Portillo, bankrolled by big oil revenues, Mexico is unprepared for a sudden drop in the price of crude, and has to sharply devalue the peso currency. Lopez Portillo nationalizes the banking sector.

- July 6, 1988. Cuauhtemoc Cardenas, son of Lazaro Cardenas, runs for president in a leftist alliance against the PRI. After initial tallies suggest Cardenas may be winning, the government says the counting system has failed. Later the PRI candidate Carlos Salinas is declared the new president. The episode goes down as the PRI’s most notorious case of vote rigging.

- July 2, 1989. The PRI suffers its first ever defeat in a state election when Ernesto Ruffo of the conservative National Action Party (PAN) is elected governor of Baja California.

- January 1, 1994. The North American Free Trade Agreement (NAFTA) comes into effect for Mexico. That same day in the poor southern state of Chiapas, an indigenous rebellion breaks out led by the Zapatista Army of National Liberation.

- March 23, 1994. PRI presidential candidate Luis Donaldo Colosio is assassinated in Tijuana. Authorities attribute the murder to a lone killer, but doubts persist to this day. Ernesto Zedillo assumes the candidacy and wins the July election.

- September 28, 1994. Francisco Ruiz Massieu, the PRI’s secretary general, is murdered. Police later arrest Raul Salinas, the outgoing president’s brother, accusing him of masterminding the killing. Raul Salinas is eventually found guilty and serves 10 years in prison.

- December 1994. Shortly after Zedillo takes over from Salinas, Mexico has to devalue the currency. It sparks a major economic and financial crisis requiring an emergency U.S. loan. The “Tequila Crisis” ripples across Latin America.

- July 1997. The PRI loses its majority in Congress in mid-term elections. No party has had one since.

- 1999. Zedillo forgoes his prerogative to name the PRI’s next presidential candidate and institutes a national primary.

- July 2, 2000. The PRI loses a presidential election for the first time, to Vicente Fox of the PAN.

- 2005. A series of state election defeats leaves the PRI in control of only half of Mexico’s 31 states.

- July 2, 2006. A divided PRI suffers its worst ever presidential election defeat, trailing in a distant third as the PAN’s Felipe Calderon wins. The defeat was the PRI’s lowest point but it then begins to regain strength as Calderon’s government struggles.

- July 5, 2009. After big gains in mid-term elections the PRI becomes the dominant party in the lower house of Congress.

Reporting by Anahi Rama and Gabriel Stargardter; Editing by Daniel Trotta, Kieran Murray and Vicki Allen