While football in Argentina has existed since the early years of the 20th century, when most of the current clubs were established, professionalism didn't start until 1931.
Unlike most Europeans league who took a break or were transformed during and after World War II, the Argentinean league has been played continuously and almost all clubs that existed during the early 30's, are still playing in 1st or lower divisions.
When professionalism was established, the 5 clubs with most championships won in the amateur era and higher attendances had the most important vote on decisions, and so they were called "The Big 5", something that still exists to this day.
This teams are : River Plate, Boca Juniors, Independiente, San Lorenzo and Racing, and all games played between themselves are considered important derbies, usually played with stadiums full of fans.
In this group, the biggest rivalries are the "Super Derby" River-Boca, and Independiente-Racing, who have their big stadiums for 40-50k fans each, separated by only 2 blocks (click here to see a google earth picture).
San Lorenzo's biggest rivalry is with another team from the capital city, Huracan, who was established in a close neighborhood, but only won 1 championship (1973) and has spent many of the last 25 years in 2nd division.
While River, Boca and San Lorenzo are from Buenos Aires, Racing and Independiente are just outside the city, in the metropolitan area, so they are considered Buenos Aires's teams as well.
This Buenos Aires teams domination has been a constant in the league, and it will continue in the 2010-2011 season, when only 4 teams will be from outside Buenos Aires and it's metropolitan area : Newell's from Rosario (306 km from Buenos Aires), Olimpo from Bahia Blanca (they are in the Buenos Aires province but 687 km from the capital city), Godoy Cruz from Mendoza (1042 km from Buenos Aires), and Colon from Santa Fe (478 km from Buenos Aires).
Since 1931 to 1967 when Estudiantes de La Plata won the league, all championships were won by the "Big 5". Since then this teams continued their domination, but Velez, Estudiantes, Argentinos Juniors, Newell's and Rosario Central among others, have won a good share of the championships.
The current situation in the league shows a parity that is difficult to find in any other league of the world : the last 8 championships have been won by 8 different teams, including Lanus and Banfield who won their first tournament ever, and Argentinos Juniors, the current champion, who won the trophy for the first time in 25 years.
The ranking of championships won is lead by River with 33, followed by rival Boca with 23, Independiente 14, San Lorenzo 10, Racing 7 (won only 1 in the last 42 years), Velez also with 7 (won 6 of those in the last 17 years) and there are also 10 other teams that were champions at least once.
River, Boca and Independiente were never relegated and played every season in 1st division, while San Lorenzo and Racing were relegated only once with San Lorenzo returning the following year (1981) and Racing playing 2 seasons in 2nd division (1983-1985).
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