By tradition, the population will suddenly quintuple, albeit by spectral souls who are revisiting the living for a three-day party. This is the ultimate fusion fest, where Aztec rites blend with the colonial Spanish version of the dance macabre and Roman Catholic saints' days.The cemeteries are filled with midnight picnickers who might literally dance on the graves in their drunken revelry.
What is riling priests and patriots alike is the growing influx of plastic Hallowe'en trinkets and rubber masks shipped from America to be hawked alongside the customary sugar skulls, marigolds and papier mache skeleton tableaus. In the big cities, such crass Yankee commercialism may soon drive out the cosy ancestor worship inherited from the Aztecs.
There may be a campaign against Caspar the Friendly Ghost, gory mummies and Sabrina the Teenage Witch, but it's a losing battle. Trick-or-treaters are beginning to go door to door, although few bother with fancy dress, and they persist for all three nights of the celebration, on Hallowe'en, All Souls' Day and All Saints Day, with shopping bags outstretched for booty. Once again, traditions are mutating.
Our skulls are not as ghoulish as they might first appear, more kitschy, made from white chocolate with icing. By marking skulls with the names of the living, it's a reminder how impermanent this life is. In the marketplace, you see all sorts of these skulls, or calaveras, for sale: some are big as pineapples, others the size of strawberries. Bakeries are stocked with pan de muertos, special bread of the dead, an over-egged confection topped with crossed pastry bones. Bright tissue paper with cut-out scenes of skeleton antics flutter everywhere. In the supermarket, chocolate skulls come wrapped in foil like Easter Eggs for the Addams Family. Death comes sugar-coated.
This motley assortment is all intended for a homely altar in the sitting room, if a family tombstone is not available. Either will be spread with the favourite snackfoods of departed relatives, as well as turkeys and fresh fruits, a bottle of booze, their preferred brand of smokes, plus candles to light the way. After the "defunct ones" are thought to have feasted to their fill the family is free to enjoy the repast and often shares it with passing strangers.
In some places, although rarely in crime-ridden urban areas, front doors are left open to encourage souls to enter, and a trail of marigold petals or blood-red flowers, the bishop's cockscomb, leads them back outside.
When butterflies, which migrate in swarms at this time of year, appear the next day, these are recognised as the returning souls. Maria Suarez, who writes on contemporary village customs says: "It is a moral obligation to remember the dead, if only once a year, when the butterflies appear."
The variety of dancing skeletons, made of sugar paste, clay or papier mache, which go on sale across Mexico, is evidence of dark humour just this side of morbid. Shift the lid of a cardboard coffin and a skeleton sits upright, grinning. Others lean up against cactus, squat and give birth to tinier skeletons, or ride in ambulances with a skull in place of the flashing light on top. One vendor displays a beauty pageant of strutting skeletons, with sashes draped over their rib-cages, and hair piled high above the skulls. Strip away our human skin and we all are alike underneath, but we hold on to our foibles.
Contemptuous nicknames for the death head are diverse: "The Pale One", "Skinny", the "Hilarious Chinaman", the "Hungry One". And nobody simply dies. You "close your beak", "hang up the tennis shoes", "go to another neighbourhood", or just "stick out your leg". Cartoons of death, often with a cheap cigar clenched between the person's teeth, are treasured.
On 1 November, the Day of the Little Angels, all dead children are tempted out with toys, sweeties, and candles fashioned from pale pink or blue wax. On the following day, more pragmatic offerings are left for departed adults. Cigars and tequila are in abundance.
Lilian Schefler, a Mexico City ethnologist, says of the customs: "Sugar skulls and movable skeletons both mock and affirm what little relevance human existence has. Death doesn't scare us because life has a way of curing our fears."