But this isn't Switzerland. The school bus didn't arrive at 7:20, as scheduled. Or at 7:30. Or 7:45. The van finally pulled up at 7:54. But the driver gave no sign anything was wrong. She was all grins and big waves, as pleased as if she'd nailed an especially difficult dismount. The punctual suffer in Mexico City, where lateness often seems as natural as gravity. Host a kids' birthday party and expect guests two or three hours late. Get to the wedding 45 minutes after the time on the invitation and you're right on the money. I've waited an hour and a half for a scheduled interview with a top Mexico City official, only to find out he wasn't going to make it at all. So much tardiness, so little time. There are many reasons. The city is enormous, with 20 million people colliding like atoms trying to get to the other side. Traffic is a monster. And, like just about everywhere else, 21st century life is full of time-eating distractions. But the main reason for the chronic lateness has to do with Mexico, which as a rule couldn't give 2 centavos about U.S.-style time expectations. Mexicans have many traits to admire -- their enterprise, their ability to make do, to endure and to enjoy life. Punctuality, though, is nowhere on the list for most of them. The Aztecs may have cared enough about time to carve their famous stone calendar, but you wonder sometimes if people here are still relying on it to get through the day. 'It's not personal. They're always late with everybody: with the judge, with the priest, with their wedding, with their mother, with their father,' said Guadalupe Loaeza, a well-known author and columnist (who arrived late for an interview in her own living room). 'It's something we cannot help.' Loaeza and others offer theories to explain tardiness in Mexico: a certain lack of responsibility, exaggerated focus on the present, generous social tolerance and plain habit. But there is something else. Time in Mexico doesn't work the same way it does in the United States, which, you'll recall, was founded by parsons and scolds who equated being on time with being good. (Time is money!) 'Here, the concept of time is very flexible,' Loaeza said. Translation: It's OK to tell someone you'll be there in a few minutes when you know there's no way this cab is getting through that traffic in under half an hour. (But you don't have to make that call until you're at least 15 minutes late, seeing as the other person is probably running late too.) The stretchiness is embedded in words whose job is to fudge, to obfuscate, to create wriggle room, to dampen expectations. Take 'ahorita,' a diminutive based on the word for 'now.' 'Ahorita' can mean 'right now.' But it's frequently used to mean five minutes from now, 15 minutes from now, half an hour from now -- anything but now now. 'Al ratito' is another diminutive (see how it works?) that means 'in a little while,' but don't start checking your watch. Appointments and numerical time estimates can be as squishy. You may be asked to show up for an office appointment at '9 to 9:30,' rather than on the dot. A 'five-minute' delay often means 15, a half-hour is starting to sound like bad news, and an hour pretty much means you're safe to cue up 'Doctor Zhivago.' But there are plenty of people in Mexico who are sticklers for punctuality. Monterrey, the business center in northern Mexico, is known to mind its clock. In Ciudad Juarez, people manage to keep appointments despite the runaway violence. 'Mexicans know when they should be punctual and which things start punctually,' said Victor Gordoa, a prominent image consultant who advises clients to be on time. 'For example, the bullfight is one of the few events in Mexico that starts exactly at 4 in the afternoon, and that's the tradition.' And the more Mexico folds itself into the global economy through NAFTA and other trade ties, the more it acts like the clock-obsessed people beyond its borders. In the business world, the two-hour-plus lunch is giving way to a hurried bite. 'You can't say, `I'll call you at 5' and then call at 7,' said Jorge Smeke, who directs business studies at the Iberoamerican University in Mexico City. 'You're beginning to see changes.' So you never know. Just when you've figured out how late you can be in Mexico, the other person is on time. An expatriate friend played it too cool the other day and missed half of a school meeting that started on schedule. There's a happy flip side to this elasticity about time and schedules. It's easy to see your dentist on short notice, even if someone with an appointment ends up waiting. And no one is likely to give you a hard time when Mexico City traffic takes you hostage. One adapts. The other day, I scheduled a phone interview for the same time I was supposed to meet someone else -- a scheduling stunt I would never have tried in the States. But like so many things here, it worked out fine. One of the people was late by 20 minutes. The other -- well, let's just say a Russian war epic could have come in handy. 