This article is from the July 2003 The Mexico File newsletter.
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The Altimeter

by Bruce McGovern 

I've been curious about the altitude of various places that I visit in Mexico. So, I bought a pocket altimeter on the Internet, and took it with me during my last visit. 

Since routine changes in air pressure cause indicated altitude to change, I think reading an altimeter is more art than science. I need more experience before I develop confidence in its use. Just before I left McAllen, it read 350 feet above sea level, instead of 30 feet, so I re‑adjusted it.  

Like Mark Twain, I missed a lot of data when I slept during the overnight trip. West of Ciudad Victoria, the bus climbs a long, winding mountain highway, then drops down to a long, flat area. The bus drives through the night at a steady 60 mph, mile after mile. I still don't know where it is, but I do know it’s at 4500 feet. 

When I arrived in Mexico City, indicated altitude was 7,150 feet, which is very close to published figures. It remained stable within 150 feet all week. 

When we took the bus to Puebla, the highest point on the trip indicated 10,050 feet. This is near where the forest fires were a few years ago. I still am not sure the pressure in the bus changed as fast as the outside air, but the needle seemed to respond quickly when we went up and down. 

My first big surprise came when we went to the family’s avocado ranch in the country. The highway from Puebla runs up, over, and around small mountains, so I’ve always believed the ranch is way “up” in the mountains. But, as I stood on that mountainside, looking “down” the long valley framing Popo in the distance, I was actually 1800 feet lower than CAPU, the central bus station in Puebla, which is about the same level as Mexico City. 

The second surprise came when we went to Cordoba. I thought we climbed over a high mountain range between Puebla and Cordoba. But, the high point was only 800 feet higher than CAPU. They seem like high mountains because in the next hour you drop 5400 feet as you drive east to Cordoba. 

And, you lose 1300 of those 5400 feet between Orizaba and Cordoba, though it seems to be flat. 

My indicated altitude in Cordoba is 400 feet lower than published. But, Lea lives on the wrong side of the tracks, which is clearly lower than the center of town. Within 36 hours after reaching Cordoba, the altimeter changed almost 200 feet.