This was one of the more interesting legs of the 2005 road trip across Mexico to see the United States’ World Cup qualifier at Estadio Azteca.

We had seen the map, and we knew we were leaving the desert, but we did not fully anticipate the massive shift in climates, once we entered Nayarit state.

Also, looking back at the installment, below, I made no mention of Culiacan’s status as the home of the Sinaloa Cartel, one of the most powerful and successful drug gangs in the world. Was I trying to be polite? Probably not.

It was possible, even in 2005, that I had not followed the Mexico narco-lord topic closely enough to know we spent our second night in Mexico in the citadel of global gangsters. I remember it as being a fairly lively, modern city; I have no recollection of feeling like I was domiciled in a monster’s den.

And then San Blas. I had never heard of it, before the trip. But it comes up now and then in the news, and it takes me back.

A few years after we stopped there, San Blas was the focus of attention after the presumably miraculous survival and rescue of three local fisherman who had drifted from Mexico across the Pacific for nine months, followed by stories from those, perhaps a majority, who doubt the survivors’ story of being out fishing for sharks.

San Blas was the first touristy town we encountered.

So, to the story:

SAN BLAS, Mexico — Strangest thing. In one tank of gas, we went from semi-arid Culiacan to swampy Nayarit state. The hint of blast furnace was replaced by amped-up sauna, complete with chirping tropical birds, palm trees and mangroves.

That’s Mexico for you. Don’t like the climate? Drive another 100 miles and you’ll be in a new one.

When the U.S. national soccer team plays Mexico in a World Cup qualifying match on Sunday, we will be in yet another of Mexico’s myriad climatic zones. The high, dry central plain. But that is two days ahead.

We can feel the match coming. A local TV station in Culiacan devoted a full 30 minutes of preview footage and commentary to Sunday’s game. On Wednesday night. Complete with a “bottom 10” of the dirtiest fouls committed by Yanks on Mexicans.

Nominated as worst: Conor Casey crashing into the Mexico goalie some years back. Dirty gringo! (As if Mexico has never cheap-shotted a Yank … or 100.)

Weird drive. Most Mexicans take off the two days before Easter weekend. Maundy Thursday and today, Good Friday. It’s part of Semana Santa, Easter week, and they take it seriously here in this overwhelmingly Roman Catholic country. It also makes for a deliciously long weekend.

The cacophonous market zone around our Culiacan hotel was eerily quiet Thursday morning. At checkout, my co-pilot Damian Secore asked the receptionist where everyone was. “Going to Mazatlan,” she said.

Going to the beach. Indeed, they were. We passed vehicle after vehicle alarmingly overloaded with people, beach chairs, coolers and even a small boat … all headed for the beach. At Mazatlan, in particular.

We skirted the popular resort, where we could see a monster cruise ship docked, and kept heading south. Along the winding coastal route. Into the jungle.

The national road dwindled to one lane in each direction. Passing was nearly impossible because the pavement was so narrow, and the curves so sharp and our teensy Chevrolet Chevy so puny.

For nearly a half-hour we were stuck behind a semi-trailer hauling scores of very unhappy hogs. We looked at them. They looked at us. There was some sort of communication there.

We should mention a bit more about driving in Mexico. The roads are, on the whole, execrable. Unless you are on a toll route, known as a “cuota” road. Rather than a “libre” (free) road.

Toll roads are in decent-to-good condition, usually two lanes each way, with a center divider, and you can get up to 85 mph, no problem. Just need to keep an eye out for the federales, who seem to be hiding behind every manzanita bush. We’ve been stopped only once so far (thinking those Baja license plates help), and warned we could kill ourselves if we didn’t slow down.

Fair enough; the speed limit is about 68 mph.

The other downside to toll roads is … the tolls. Serious money. To make a guess? We’ve spent $100 in tolls (usually $4-10 per stop), and we’ve done only about 60 percent of our 1,800-plus miles so far on the “cuota.” Seems as if there’s another toll booth every half hour.

Gas usually is expensive here, but with the run-up in U.S. prices, petrol actually is a bargain, south of the border. We paid $2.19 a gallon Thursday, figuring the peso at about 11.5-to-1 vs. the dollar. Caught a break there.

We’re in San Blas because we couldn’t find a hotel anywhere around Mazatlan. The Semana Santa and all of Mexico going to the beach, remember?

San Blas is a fishing town of about 10,000, with an old, semi-rundown city center, the sort of crumbling, white-washed adobe you would expect in a Clint Eastwood spaghetti western.

But the town is right on the beach, in a prime spot for whale- and bird-watching (the “putto” bird is a prime attraction).

It also is a prime location for unpleasant flying insects; bug bites in this swampy bit of terra infirma are a prime topic of conversation.

San Blas, the patron saint of throat diseases (true story) was a missionary in Turkey, according to Josefina Vazquez, manager of the hotel here.

Josefina isn’t a huge soccer fan, but even she knows about the Sunday match. “I’m afraid Mexico will lose,” she said in English perfected as an exchange student at Paramount High School in 1976. “This is bad against such a young soccer country as the United States.”

She suggested we speak to the wait staff at the attached restaurant. Serious “aficionados,” she said. “They never miss a game.”

Jorge Banuelos and Julio Virgen said they have been thinking of Sunday’s match “for weeks.”

“Losing to the U.S. is very bad because Mexico has a tradition in soccer, and the U.S. is new,” Jorge said. “It’s very important to Mexico, because all Mexican families are going to watch the match.”

Said Julio: “If Mexico loses, the players don’t deserve to wear the national jersey. The whole country expects Mexico to win.”

Back in the states … nearly the whole country doesn’t even know Sunday’s match is on. Just another of the cultural gulfs between two not-always-neighborly neighbors.

Tomorrow: From San Blas to Guadalajara.