The Primera División has been using different formats for its championships, from a double round-robin tournament (1891 to 1966) to a single round-robin that would become the standard in Latin America, the Apertura and Clausura. In the particular case of Argentina, the Apertura was contested in the second half of the calendar year, and the Clausura was played in the first half of the following year (in order to synchronize the seasons with those of the European football). Different formats used also included the organization of Metropolitano and Nacional championships, that lasted from 1967 to 1985.