At a crossing near Nogales, the cars idle nose to tail while a vendor works the line with bags of cut mango. That scene never makes it into a State Department alert. The latest U.S. Embassy Mexico travel warning arrived with the tone of a weather report: expect big crowds, heavy traffic, longer travel times. The World Cup starts next week, spread across sixteen cities in Canada, the United States, and Mexico, and the advisory has done the responsible thing by telling you that getting from one place to another in 2026 will involve sitting in your car. Fair enough. But an alert is a thin document. It can tell you a road near Nogales gets congested. It cannot tell you who lives along it, what they sell, whether they are weighing a move north. That gap is exactly the space Paul Theroux spent years driving through, windows down.
A travel warning assumes that risk is a property of geography. This route is dangerous; that crossing is congested; plan accordingly. The logic works if your only goal is to arrive intact, and you should want that. It also skips the part where a border is where people earn a living, raise families, and decide whether their future sits on this side or the other. The crowds an alert flags are made of individuals with reasons. The traffic at a checkpoint has a history. Strip those out and you have a color-coded sketch of a place that several million people call home. Theroux's method is to talk to the people standing inside that sketch.
On the Plain of Snakes follows Theroux as he drives the full length of the US-Mexico border, then turns south into the back roads of Chiapas and Oaxaca. He is in his seventies when he does it, which gives the book a certain stubbornness. He could be home. Instead he is idling at checkpoints near Nogales, watching patrol presence thicken, noting how the desert highways of Sonora decide where delay and tension pool. The same instinct that shaped his earlier American road book, Deep South, is at work: stop the car, start a conversation, stay longer than is comfortable.
He talks with residents doing the arithmetic of going north against the arithmetic of staying, and the specific fears attached to each. He sits with Zapotec mill workers in the highlands. He turns up at a Zapatista gathering far from anything a tourist would stumble onto. These are the reporting, not scenic detours, and they accumulate into a portrait of a region where mobility, migration, and ordinary daily life cannot be pulled apart. The border, in his telling, is a wide zone of constant motion rather than a single line, and the congestion a World Cup will worsen is one more pressure on roads that already carry enormous human weight.
When the advisory says expect heavy traffic, Theroux has already shown you what that traffic is made of. I will be honest about the friction. Theroux's persona can grate. He is a practiced grump, and the book sometimes leans on the seasoned-traveler pose in a way that parks him a little too comfortably at the center of every encounter. There are moments when you wish he would step out of the frame and let a Zapotec mill worker finish a thought without his commentary wrapped around it. The affection he brings to ordinary people is real, but it arrives filtered through a sensibility that decided in advance what kind of book this would be.
That is the cost of the method, and it is worth paying. A more neutral reporter might hand you cleaner facts and less feeling. Theroux gives you the feeling, the long uncomfortable pauses, the mezcal, the Day of the Dead, the sense of a country that refuses to rearrange itself around your itinerary. If you want to understand why certain routes carry risk and how communities live alongside the crossings, his first-person stubbornness turns out to be the right instrument, even when the man holding it is being insufferable.
If the World Cup has you treating Mexico as a logistics problem to be solved, this book is a quiet corrective. Theroux will not make the crossings less crowded or your drive any shorter. He will, if you let him, swap the color-coded abstraction for a place with weather, work, opinions, and a lot of people who were there long before the advisory and will be there long after. Worth a few hundred pages before you go.