*snicker*
Yeah, that always seemed absurd to me. Of course, Mexico was in a continual state of civil war during the later 19th and early 20th century, with just a period of liberal dictatorship by Porfirio Diaz. Diaz generally ran unopposed for reelection, but in his last campaign was challenged by a young, hmm, doctor I think, Madero. There was an elation rarely seen before about the new guy. Of course, Diaz fixed the election, but not just a little bit, really obviously, and also at some point threw Madero in jail, where he died in custody. The country went up in flames, Diaz fled into exile with a pile of loot, and died of old age. After a period of fighting from end to end, a couple of generals wound up in power, they and theirs drafted a constitution which limited the president to one term, and then one of them ran for president. He won, served, retired, and the other one ran and won. Near the end of his term the other one ran again, the constitution was amended to permit it, he won the election, was assassinated I believe, and another civil war began. But the current constitution was written after everything simmered down, circa 1920, and everything seems to be okay, other than the coast-to-coast drug cartel violence and top-to-bottom political and police corruption. ;’) PRI was the first party to organize, campaign for, and win national majorities, which permitted it to rig things in its favor (remember, the model back then was up-and-coming socialism); PRI has as its official colors the same found on the flag of Mexico, and no other party is permitted to use them.