The 643-mile stretch of Interstate 25 between Las Cruces, New Mexico, and Denver skips across time and terrain like few other American trails.

The highway passes through settlements that date back to before Columbus and through brand-new housing tracts with Subarus in the driveway. It cuts through lush valleys and staked plains, metropolises and ghost towns, tree-blanketed mountains and punishing deserts. Through majority-Mexican villages, and suburbs whiter than the Rocky Mountain snowpack.

Travelers have trekked this passage for centuries, always with care. Conquistadors named the area around the southernmost section the Jornada del Muerto — Journey of the Dead Man — because of how unforgiving it was. To this day, drivers try to rush over the Ratón Pass (elevation 7,834 feet) that separates New Mexico and Colorado before sunset, lest they get caught in bad weather. And that weather: It can switch from sleet to fog to dust storm to snow to rain, all in the space of a couple of miles.

It’s not a route for the faint of heart. But I did it. And my fuel was the one thing that unites the disparate communities along the way — chile.

Chile peppers are the Southwest’s most famous gastronomic expression: grown and packed and used for decoration, grilled and dried and frozen, and eaten all year in the region. On I-25, however, “chile” is as varied as the land and people. It’s the pepper, for sure, but also a salsa that can be as thick as gravy or as thin as water, mellow or scorching. “Chile” also appears as a cheeseburger, a snack, a meat rub. A full meal or an appetizer. A bowl or a plate. A soup or chicken-fried steak or burrito drowned (“smothered” in local parlance) in it. Red or green chile or both, a style called “Christmas.” Dessert. Heritage. Life.

Over three days, I saw and tasted how restaurants along the Chile Highway approach their spicy muse. The dishes here rarely venture far from what’s now I-25 because their essence is tied to the chiles grown along the route. No other peppers in the world will do, so home cooks and chefs and packing companies roast freshly harvested green ones every fall to use immediately (and freeze leftovers for the future), or dry the red ones to make powders, flakes, or ristras (vertical bouquets of dried peppers). Either way, a guaranteed, year-round supply is always near.

From this shared ingredient bubbles up a dazzlingly diverse food scene that stretches way beyond Santa Fe and Hatch, the two stops on the Chile Highway that food media focus on at the expense of the rest. Great grub at American Indian-run gas stations. Burger empires. Hyper-regionalism — Cruces-Mex, Den-Mex, Pueblo-Mex, and so much more. (Read Eater’s Definitive Guide to Santa Fe Green Chile.)

I ended up eating “chile” 38 different ways — and I could’ve done more. But caution to the curious: Take the trip in doses, not in one fell swoop like me. Like Icarus, I flew — or rather, ate — too close to the heat. At times, I felt like the trip might actually turn me into a living Human Torch. But like the Phoenix, I rose from the proverbial ashes, spitting nothing but fire.

And the ordeal was worth it.

To outsiders, the food of the Southwest is synonymous with Mexican, mostly because the cuisines share the same foundation: tortillas, combo plates, an emphasis on meats, and especially chiles. But over the past 400 years, residents have fused the traditions of the region’s three main ethnic groups — Mexican, white, and American Indian — to create a gastronomy that belongs to all three yet stands on its own.

These foodways found their most lasting expression in New Mexico, where the state’s Hispanics (known as Hispanos, because many trace their ancestry to conquistadors) settled the northern part of the Land of Enchantment in the 1600s, remaining in relative isolation until the federal government began to pave roads connecting Albuquerque and Santa Fe to the greater U.S. after World War II. Removed from constant replenishment from Mexican migration like, say, Cal-Mex and Tex-Mex, much of New Mexican food remained largely frozen in time.

Or so I thought.

Before my expedition, I vowed not to commit the sin of so many before me: to think of New Mexico as a place where time ran slower than in the rest of the country, and the culture was fossilized, and therefore ripe for exotification.

“It is the Great American Mystery — the National Rip Van Winkle — the United States which is not United States,” wrote Charles Fletcher Lummis in his 1893 book Land of Poco Tiempo. “Why hurry with the hurrying world? The ‘Pretty Soon’ of New Spain is better than the ‘Now! Now’ of the haggard States.”

Even when Southwestern cuisine had its national heyday in the 1980s — when chefs like John Rivera Sedlar and Mark Miller garnered attention for fusing local ingredients with French techniques — reporters and critics depicted the movement’s acolytes as necromancers resurrecting dormant, overlooked riches long forgotten by the locals.

That idea, however, robs the Chile Highway’s denizens of their agency. The people here easily change with the times while keeping true to their chile heritage — it all depends on who’s doing the eating and where. That pride and flexibility characterized my first day.

My journey began in Belen, a city of about 7,000 near the geographical center of New Mexico. At Sandra’s New Mexican Restaurant, I ordered a bowl of posole, which called back to the old ways, spelled with an S (like Spanish friars wrote it out in the 16th century) instead of a Z (the way you find it written out today across Mexico). There was no oregano or cabbage or even lime as toppings — just pork chunks and hominy. And the posole came white, with red chile on the side.

I wasn’t familiar with this presentation, but it didn’t matter: Sandra’s posole was porkier than ramen — the chewy meat, the unctuous broth, the fat kernels. Splashes of red chile opened up its flavors further.

But before I could romanticize New Mexican cuisine as an atavistic treasure, I next gorged on Milly’s Burrito Plate at Alejandro’s Café, five minutes down the street: a great beef burrito buried under french fries and smothered in a fine green chile. It was heavy for breakfast, but it didn’t take long for me to realize that hefty, hearty breakfasts are common throughout New Mexico. Mornings are chilly all year, and there’s nothing like spice and starch to insulate your insides.

My next stop was about 45 minutes south, at San Antonio Crane, named after the small city of San Antonio, as well as the sandhill cranes that migrate to the nearby Bosque del Apache National Wildlife Refuge every winter. The restaurant, a converted house, was slammed, which explained the slow service for my open-faced smothered hamburger, topped with more fries.

There were no arguments about authenticity or heritage at Sandra’s, Alejandro’s, or San Antonio Crane; there was chile. And that was all I needed.

Two hours later, I rolled into Las Cruces and La Nueva Casita Café, which has served New Mexican classics since 1957. Families fresh from church or dressed in Dallas Cowboys gear sat around the ample dining room slurping menudo with toast on the side, an unusual pairing — and another nod to mutability.

I went with the huevos compuestos, a specialty of southern New Mexico. Two small tostada shells filled with carne adovada, topped with eggs any style, and drizzled with chile, huevos compuestos are like a crunchy Hispano eggs Benedict. This version was saucy and savory and superb, with chile two ways: as a sauce and as carne adovada, pork that’s baked with red chile powder and other spices and serves as the de facto meat of the Chile Highway. Think al pastor, but better.

At La Nueva Casita, the adovada was bright with the freshness of chile sourced from Hatch, the self-proclaimed Chile Capital of the World and the one thing most foodies know about New Mexico. Those peppers made a cameo in my dessert at Caliche’s Frozen Custard, where I chose the New Mexican sundae: two scoops of vanilla custard, layered with candied Hatch peppers and salted pecans. The crunch and sweet and spice made it one of the best frozen desserts I’ve tasted in years.

I visit Hatch every summer, so this time I bypassed it in favor of a challenge. For years, I’ve passed a billboard on I-25 for Arrey Cafe that screams, “World’s Finest Green Chile Cheeseburger.” Now, I had the chance to put that claim to the test.

The green chile cheeseburger is the Chile Highway manifest. It didn’t even exist until after World War II. But New Mexicans quickly fell in love gracias to Blake’s Lotaburger, a local obsession on par with California’s In-N-Out and Texas’s Whataburger; there are 28 Lotaburger locations in Albuquerque alone.

New Mexicans quickly embraced this relative newcomer; New Mexico’s Tourism Department promotes a Green Chile Cheeseburger Trail to attract tourists. It’s just a cheeseburger with green chile on it. But therein is the beauty: Green chile is the condiment you never knew a burger needed. Diced or whole sauteed peppers are spread across the patty — past and present New Mexico, snug between two buns.

San Antonio’s Owl Bar & Cafe claims to have created the burger to feed the scientists who worked on the Manhattan Project. It was closed on the Sunday I visited, so I settled for Arrey.

Its roadside ad is almost correct. Arrey makes a great burger — the patty is loosely packed, the Hatch chile is fleshy and piquant, and their secret sauce is a relishy green salsa that ramps up the heat. The double-fire of green chile and salsa lingered longer than I thought it would, but I didn’t think much of it then.

It was a harbinger of the hell settling into every cell of my being.

When I left Arrey, I realized I faced a problem: All the restaurants I wanted to visit were either not open on Sundays or closed by 3. So I sped off to Albuquerque, grabbing any good bites I could find along the way.

I found plenty. A green chile Philly cheesesteak at Johnny B’s in the town of Truth or Consequences, New Mexico, that I dunked into their sturdy cup of red to create a New Mexican French dip. A Frito pie, a glorious mess of crunch, cheese, and Socorro-style red chile sharper and smokier than Hatch, at the 24-hour El Camino Restaurant, whose wooden booths, kachina figures, and dive-y bar make it look unchanged since its 1963 debut. A juicy adovada burrito in the Los Lunas outpost of the statewide chain Burritos Alinstante, New Mexico’s second-best food empire after Blake’s.

I stopped for gas at the Isleta Travel Center, just outside the Pueblo of Isleta, “Pueblo” in New Mexico referring to what the rest of the United States would call a reservation. New Mexico has some of the best gas station food in the country, because Native American tribes run many of them and frequently stock local goods. The Isleta Travel Center sold green chile piñon nuts last time I visited; this time, I grabbed a bag of Bar X Brand green chile carne seca, dried beef that feels like dehydrated tissue paper but reconstitutes lusciously in your mouth. And, unlike other jerkies claiming to light up your mouth, Bar X brought the fire.

I rolled into Albuquerque at nighttime, but managed to score an adovada plate at Duran Central Pharmacy, and some adovada-stuffed sopaipillas at Sadie’s, two local standbys. After so much savoriness, I needed something sweet, so I swung by Frontier Restaurant, a legendary late-night diner across from the University of New Mexico. Under the gaze of multiple portraits of John Wayne, I picked at one of their massive cinnamon rolls. But I couldn’t shake the chile: Frontier has two large vats of complimentary red and green. I dunked chunks of the rolls in each. Chile as frosting? Divine.

Undergrads of all ethnicities filled up at the chile station. I felt a tingle in my chest as I beheld a post-racial America brought together by the power of red and green.

Or was it all the chile pulsing through my veins?

Every time I visit ABQ, I stop by Barelas Coffee House. This is where friends took me the first time I visited the Duke City, about 12 years ago, and taught me that “red” and “green” in the Southwest mainly concerns chile. A savory bowl of either at Barelas, with their billowy flour tortillas to sop up every last stain, would make you an instant convert to the city, the state, the chile, the everything.

I started Day Two with a bowl of green, then picked up some biscochitos (anise-flavored shortbread cookies) from the venerable Garcia’s Kitchen chain. I needed some snacks to tackle my longest stretch of the drive: 378 miles, ending in Colorado Springs.

It would nearly become my end, period.

I pumped gas at the Warrior Fuel II station in Bernalillo, run by the Santa Ana Pueblo. Tribes across New Mexico have diversified their business holdings this decade and opened restaurants to promote indigenous eats and offer economic opportunities for tribal members. Such a strategy both preserves the past and ensures the future.

Business was popping at Warrior Fuel II, as construction workers and commuters grabbed to-go breakfast burritos from a display case, or served themselves green chile stew from pots. I ladled myself the latter. Pork, potatoes, and strands of pepper, it was like a fiery fall harvest in a Styrofoam cup, no salsa necessary. Even better was the Pueblo Restaurant inside San Felipe Travel Center in Algodones, run by the San Felipe Pueblo. The bowl of red was tasty, but more memorable was the Pueblo taco — fry bread, ground beef, and green chile, fused together with cheese. Even though this is a choice fraught with colonial implications, other tables enjoyed the same, so I set aside my social justice radar and joined in.

Santa Fe gets so much attention that I decided to continue along I-25, making an exception for Cafe Fina, a cute coffee shop on the outskirts of the City Different, whose huevos divorciados, a Mexico City desayuno of eggs and ham on a lightly fried corn tortilla, were Hispano-ized with Christmas chile instead of red and green salsa. Afterward, I wound my way around the snow-dusted Sangre de Cristo Mountains to the hardscrabble hub of Las Vegas, New Mexico. I liked my juicy, smothered adovada burrito at Maryann’s Famous Burrito Kitchen, but far better was a spot I didn’t expect much from: Charlie’s Spic & Span.

It looks like a tourist trap, with neon signs and goofy paintings, like the cover of Whipped Cream and Other Delights. But behind all the kitsch is a great diner. The adovada skillet, sizzling with runny eggs and potatoes, was breakfast at its best. The flour tortillas were so fluffy that I grabbed a still-steaming bag of them from a table near the cashier on the way out.

But after Charlie’s, I ran into bad luck: The restaurants at every town between Las Vegas and Raton were closed. The hangry was real when I finally reached Enchanted Grounds Espresso Bar in Raton, a cowboy town on the old Santa Fe Trail. It was 2 p.m., and the cafe had run out of food for the day.

“Where else should I eat?” I asked the nice woman behind the counter.

“Nowhere today, really,” she responded. “Everything good is closed on Monday. And everywhere closes around this time. Pretty silly, if you ask me.”

I bought some hot chocolate to wash down buttery green chile piñon brittle and my disappointment. Off to Trinidad, Colorado, a funky mining town that, according to free magazines in the local convenience stores, had been a hub of Mafia activity during prohibition. There were more Italian restaurants than Mexican ones in downtown Trinidad, and pasta was the star at Tony’s Diner.

I also found something that’s rare on Southwestern menus: a bowl of chile caribe. It’s red chile made with dried peppers instead of fresh, which creates a spicier, deeper flavor. It was one of the best bowls I’d ever tasted, and a great introduction to Colorado-Mex.

Hispanos settled southern Colorado in the 1850s, and many manitos (the nickname their descendants go by) feel greater kinship with northern New Mexico than they do with Colorado. The result is food as removed from New Mexican food as New Mexican is from Mexican, with added influence from European immigrants (especially Italians), whose presence in the area goes back more than a century. It’s one of the few branches of the Mexican food tree where such a mix causes little grumbling — because chile.

Take Corine’s Mexican Restaurant in Walsenberg, a city of 3,000. Open since 1957, the diner’s best entree is Pollo de Colorado, fried chicken strips topped with a thick red chile. The result tasted like Mexican schnitzel, and simultaneously lifted my tired body while weighing down my gut.

The chile was even better at Three Sisters, a honky-tonk bar in Colorado City. Prominent on the menu was a bowl of Pueblo-style green made from the Mirasol pepper, which manitos grew for over a century and is currently being prepped for its national day in the sun by Italian-American farmers in the San Luis Valley.

Sorry, New Mexico: Pueblo peppers and their incarnations beat all of your chiles. Just a cup of it at Three Sisters showed why — it was more intense than Hatch, more pungent than Socorro, and as rare as Chimayó. (Colorado growers only harvested about 600 acres of peppers last year, compared to the 8,000 or so that New Mexico registered.)

Mirasol love was all over Pueblo, a city with its own distinct cuisine. There, the most beloved treat is the Slopper, a hamburger patty in a sea of green chile: bar food, bar none. Downtown’s Gray’s Coors Tavern claims to have invented it, and their version is particularly wonderful.

Better were the chicken tacos on white at Polito’s Beer Barrel, a neighborhood dive just a minute away from one of the last operating steel mills in what was once called the Pittsburgh of the West. The “white” refers to flour tortillas, and Pueblo makes them thick and salty, then fries them for tacos so that the end result tastes like pita chips. As a side, Polito’s offered fideo, Mexican-style vermicelli noodles which I’ve eaten my entire life in soup, but were here closer to a cumin-heavy spaghetti. Fried flour tortillas also made the base for a gigantic tostada at Estela’s Mill Stop Cafe, with a side of rice so soaked in tomato sauce that it was basically a broth.

I left Pueblo with a Reskie Burger — patty, pimento cheese, and extra Pueblo chiles — from Bingo Burger, and a desire to find ever more Pueblo-Mex. But I could only take one bite before my body finally shut down.

Bluntly put: You try eating chile 27 ways over just two days. It hurts.

The 45-minute drive to Colorado Springs was one of the most uncomfortable of my life. My digestive tract was fine; it was the rest of my body that burned. My eyes felt like they could shoot an optic blast like Cyclops from the X-Men. My skin was warm; my sides began to spasm.

I didn’t sleep that night, constantly waking to the thought of green and red Christmas-ing me with a slow, agonizing, delicious death.

The dish that started my next day, at King’s Chef Diner, looked simple enough: a small bowl of green chile stew, made from Mirasol peppers. No meat, no beans, no nada — just the chile as a soup, with flour tortillas on the side. I had overslept from the previous night’s pain. But with one sip, my troubles disappeared.

What a bowl! Thick, like a comforting Mexican hot chocolate. I was now so hungry that I even scarfed down a huge breakfast burrito at the nearby Rudy’s Little Hideaway, the Pueblo green chile inside zippy and caliente. Rejuvenated, I zoomed to Denver for lunch at La Fiesta. Along a highway defined by restaurants with haphazard hours, La Fiesta probably has the weirdest: open only for lunch, Monday through Thursday; until 9 p.m. on Fridays; and closed on weekends. La Fiesta is special to me, though, because this is where I first tasted Den-Mex over a decade ago.

The Mile High City’s contributions to Southwestern food aren’t just a galaxy apart from Mexican; they’re an entire universe. Chiles rellenos are enveloped in wonton wrappers, then fried. The green chile has an orange tint, not as a shoutout to the Denver Broncos, but because of all the tomato. It’s more like a stew than a sauce, yet it’s consistently hotter than chile in New Mexico (albeit less hot than Pueblo-style).

The region’s favorite supper is the Mexican hamburger — a bean-and-chicharron burrito, smothered, with a hamburger patty in the middle and cheese melted on top. Even Mexican restaurants, run by Mexican immigrants, carry it to ensure they make rent.

I got my regular order at La Fiesta: the namesake combo platter of a chile relleno, bean burrito, and cheese enchilada, everything greasy and hefty and smothered in green. I visited Las Delicias, a Denver chain that splits the difference between Den-Mex standards and meals like carne asada and carnitas. Then I drove to Colorado Springs, intending to slowly make my way back up I-25 to eat at the mountain towns along the way.

This was a mistake. Most of their Den-Mex restaurants close after lunch, which meant I skipped over multiple cities as I returned to Denver. So sorry, Monument. Lo siento, Castle Rock. Your fault, Centennial.

I did find something interesting at Charito’s House in Larkspur, home of Colorado’s Renaissance Festival. It was a straightforward Mexican restaurant — the owners are from the state of Puebla, and their tacos were great. But their menu impressed me. Under the Lo Traditional section were crispy rellenos, Mexican hamburgers, and green chile.

Traditional to I-25 and nowhere else.

Mexicans have a reputation as culinary chauvinists (much-deserved, I say: Please @ me) who want their cuisine to stay in eternal stasis and who are triggered by the very thought of peas in guacamole. But the Chile Highway presents a third way that even the Mexican immigrants who ran Charito’s could understand: Den-Mex wasn’t their Mexican food, but rather, a long-lost cousin happy to reconnect, wanting only respect from its elders.

Respect we should all give.

My chile belly was grumbling again by the time I hit Urban Sombrero in Englewood, a sports bar surrounded by economy hotels where the Den-Mex is not dialed down. They chopped up and fried chiles rellenos, the easier to dunk them in a better-than-expected green chile. I calmed down with a potent green chile martini at national chain Chuy’s Tex-Mex in Westminster.

This gave me the second wind I needed to complete my Den-Mex holy quartet, the places I always make pilgrimages to whenever I’m in town. A bean and cheese burrito with green chile at Santiago’s, a chain with nearly 30 locations around Denver, was far better than its longtime local rival Chipotle (whose headquarters relocated to Orange County, California, in 2018). A fabulous pork chop prepared adovada-style was smothered in meaty green chile at Señor Burritos. Two moist pork tamales were bathed in green at El Noa Noa, the restaurant where I once dined with anti-immigrant former congressman Tom Tancredo before debating him at a Chicano theater across the street.

I concluded my odyssey with the best Den-Mex of them all: a Mexican hamburger at the Original Chubby’s. I crowned it America’s best Mexican dinner in my 2012 book Taco USA: How Mexican Food Conquered America, because I thought Chubby’s represented Mexican food at its finest — surprising, filling, bueno, and proudly regional.

Chubby’s was a small stand when I covered them, and I fondly remember how you could only order to-go and they covered it with two paper plates stapled together so the chile wouldn’t spill. Since then, the owners have knocked down the original building and erected a multihued palace complete with seats and big-screen TVs. The neighborhood around Chubby’s is quickly gentrifying, but they’re still open from 6 in the morning until 2 a.m., 3 a.m. on weekends, with unending lines of blue-collar patrons.

The Mexican hamburger remains awesome — sticky and mushy and smothered in so much chile that the carton is overflowing. As it should.

Like many of its fellow Chile Highway denizens, the Mexican hamburger will probably never be popular anywhere else, and Chubby’s has never received any national accolades. It’s too working-class, too homely, too fattening, and just not Mexican enough.

Too I-25.

America’s loss. The Southwest’s chile game is strong, and I’m more of a convert than ever. And that’s why, even after eating 37 previous chiles in 60 hours, with my gut bloated and my esophagus irritated, I gobbled up my entire Chubby’s Mexican hamburger — and my appetite has never been happier.

Gustavo Arellano is a features writer at the Los Angeles Times and author of Taco USA: How Mexican Food Conquered America .

Fact checked by Pearly Huang

Copy edited by Rachel P. Kreiter