I was that old gringo. I was driving south in my own car in Mexican sunshine along the straight sloping road through the thinly populated valleys of the Sierra Madre Oriental – the whole craggy spine of Mexico is mountainous. Valleys, spacious and austere, were forested with thousands of single yucca trees, the so-called dragon yucca (Yucca filifera) that Mexicans call palma china. I pulled off the road to look closely at them and wrote in my notebook: I cannot explain why, on the empty miles of these roads, I feel young. And that was when I saw a slender branch twitch on the ground; it lay beneath the yucca in soil like sediment. It moved. It was a snake, a hank of shimmering scales. It began to contract and wrap itself – its smooth and narrow body pulsing in the serpentine peristalsis of threat, brownish, like the gravel and the dust. I stepped back, but it continued slowly to resolve itself into a coil. Not poisonous, I learned later. Not a plumed serpent, not the rearing rattler being gnawed by the wild-eyed eagle in the vivid emblazonment on the Mexican national flag. It was a coachwhip snake, as numerous on this plain as rattlesnakes, of which Mexico has 26 species – not to mention, elsewhere, milk snakes, blind snakes, rat snakes, pit vipers, worm-sized garden snakes and 10-foot-long boa constrictors. Now in his 70s, Theroux embarked on one of his greatest journeys: to crisscross the US-Mexican border  The joy of the open road – joy verging on euphoria. “Behind us lay the whole of America and everything Dean and I had known about life, and life on the road,” Kerouac writes of entering Mexico in On the Road. “We had finally found the magic land at the end of the road and we never dreamed the extent of the magic.” But then, driving onward, reflecting on the old twisted trunks of the yuccas and their globular crowns of spiky sword-like leaves (“The leaves are erect when they are young but they become arched when they get older,” a botanist writes, seeming to suggest a fogeyish image), each a solitary stick in the asparagus family – and it does seem like a succulent spear that’s swelled to become a desert palm rooted in sand, tenacious but bending as it ages. I also think, It’s been a hard summer. Unregarded, shunned, snubbed, overlooked, taken for granted, belittled, mocked, faintly laughable, stereotypical, no longer interesting, parasitical, invisible to the young – the old person in the United States, and the man and writer I am, is much like the yucca, much like the Mexican. We have all that in common, the accusation of senescence and superfluity. Feeling invisible and shunned, Theroux felt a kinship in his old age with how many Mexicans are portrayed by the US media So, I can identify. But leaving home for Mexico at a time when I feel peculiarly ignored and weakened in status is not sad or lamentable. It is the way of the world. This is a triumphant mood for a long trip, just slipping out and not telling anyone, and fairly sure that no one will notice I’ve gone. I think of myself in the Mexican way, not as an old man but as most Mexicans regard a senior, an hombre de juicio, a man of judgment; not ruco, worn out, beneath notice, someone to be patronised, but owed the respect traditionally accorded to an elder, someone (in the Mexican euphemism) of La Tercera Edad, the Third Age, who might be called Don Pablo or tío (uncle) in deference. Mexican youths are required by custom to surrender their seat to anyone older. They know the saying: Más sabe el diablo por viejo, que por diablo – The devil is wise because he’s old, not because he’s the devil. But “Stand aside, old man, and make way for the young” is the American way. As an Ancient Mariner of a sort, I want to hold the doubters with my skinny hand, fix them with a glittering eye, and say, “I have been to a place where none of you have ever been, where none of you can ever go. It is the past. I spent decades there and I can say, you don’t have the slightest idea.” On my first long trip – to central Africa, 55 years ago – I was exhilarated by the notion that I was a stranger in a strange land: far from home, with a new language to learn, committed to two years out of touch, teaching barefoot students in the bush. I was to remain in Africa for six years, learning how to be an outsider. My next teaching job was in Singapore, and when that ended after three years, I abandoned all salaried employment and became a resident in Britain for 17 years, carrying the compulsory Alien Identity Card. Partly from passionate curiosity and partly to make a living, I kept travelling. The risky trips I took in my thirties and forties, launching myself into the unknown, astonish me now. One winter I was in Siberia. I went overland to Patagonia. I took every clanking train in China and drove a car to Tibet. I turned 50 paddling alone in my kayak in the Pacific, threatened by islanders, tossed by waves, blown off course in a high wind off Easter Island. Even travelling from Cairo to Cape Town in 2001, and stopping in Johannesburg for my 60th birthday, seems an unrepeatable journey – at least by me, when I remember how I was fired upon by a shifta bandit in the Kaisut Desert near Marsabit, and being robbed in Johannesburg of my bag and everything I owned. A decade later, on an African trip for a sequel to that book, resuming in Cape Town and heading for the Congo border, I turned 70 in the Kalahari Desert and defended myself against oafs in the stink and misery of northern Angola. All these trips, 10 of them, became books. The author first ventured to Mexico via Nogales, where a fence separates many families along the US-Mexico border  “Write the story of a contemporary cured of his heartbreaks solely by long contemplation of a landscape,” Camus wrote in his Notebooks. Heeding that advice (which has always been a mantra to me) at a time when I believed I might be done with long journeys, I took to my car and went on a two-year trip through the back roads of the Deep South, with a book in mind. I was rejuvenated in the precise sense of the word, tooling along in my car, made to feel young again. In those years, traveling in the South, I made a detour and crossed the Mexican border for the first time, at Nogales. It was a travel epiphany that woke me to a new world. I marvelled how, pushing through an Arizona turnstile in a doorway blowtorched into a 30-foot iron fence, in seconds I had stepped into a foreign country – the aroma and sizzle of street food, the strumming of guitars, the joshing of hawkers. “Just across the street Mexico began,” Kerouac writes. “We looked with wonder. To our amazement, it looked exactly like Mexico.” I met some migrants then, Mexicans intent on slipping across the border, others who had been deported. Knowing the risks that migrants took emboldened me, and hearing nothing but ignorant opinion about Mexicans, from the highest office in America to the common ruck of barflies and xenophobes, I decided to take a trip to Mexico. But I have not found a traveller or commentator, foreign or Mexican, who has been able to sum up Mexico, and maybe such an ambition is a futile and dated enterprise. The country eludes the generalizer and summariser; it is too big, too complex, too diverse in its geography and culture, too messy and multilingual – the Mexican government recognises 68 different languages and 350 dialects. An implication in all books about the country is that, though Europeans successfully emigrate to Mexico and become Mexican, no American can follow suit: the gringo remains incorrigibly a gringo. In practice, this is not a hardship but amounts to a liberation. Consider the ritualised banter of the sort that social anthropologists describe as “the joking relationship.” This foolery is practiced in Mexico to a high degree of refinement. Mexicans allow gringos the singularity to be themselves by trading jolly insults in order to emphasise differences, using the humour of privileged disrespect to avoid conflict. Or, as the anthropologist AR Radcliffe-Brown (the definer of this social interaction) put it, “a relation by two persons in which one is by custom permitted, and in some cases required, to tease and make fun of the other, who in turn is required to take no offense.” Owing to Mexican generosity and good humour in a culture that values manners, especially the manners that govern jocular teasing, an American who accepts the role of a gringo is licensed in his gringoismo. A gringo who doesn’t abuse that status is given the latitude to be different. Most of the time Mexicans use the word “gringo” without much malice. (Gabacho is the insulting word in Mexico for gringo; in Spain, it is a way of rubbishing a French person.) And so the tradition of gringos finding refuge in Mexico is old, and especially now there are permanent communities of gringos all over Mexico, retirees and escapists who have no plans ever to go home, who find it very simple to show up and stay for years. This Mexican hospitality to gringos is in ironic contrast to the present ubiquity of Mexicans who are demonised and fenced in, stamped as undesirable, considered suspect, and unwelcome in America. Glaring paradoxes like that, and the repetition of stereotypes, also provoked me to take this trip, hoping for more insights in the foreign country through the doorway in the high fence at the end of the road. And there was my anxiety that my driving days are numbered, that my writing life had stalled, that I kept being reminded I was old, and I knew that a road trip would lift my spirits and release me from the useless obsession of self-scrutiny and induce in me (as the English writer Henry Green put it in Pack My Bag) “that blessed state when you forever cease to give a damn.” What I intended was a jaunt from one end of Mexico to the other, the opposite of a downfall, which is a dégringolade; rather, a leap in the dark, driving away from home, to cross the border and keep going until I ran out of road. Even the most lighthearted journey to Mexico becomes something serious – or dangerous, tragic, risky, illuminating or at times bowel-shattering, and in my case it was all of those things. But no sooner had I gotten behind the wheel than a feeling came over me that was like being caressed by a cosmic wind, reminding me of what travel at its best can do: I was set free.