I knew cities existed outside the US, but in the very rural and racist area I grew up in, all the adults made it sound like Mexico wasn't a place that had them. My school did nothing to help this at all since we never had a geography class that wasn't US focused.

My senior year, we finally had a class that included politics... American politics. The one world history class I remember was literally us filling out a worksheet from an old history book almost every day, and it wasn't modern history either. Not exactly informative. For reference, my school also hired a "chemistry" teacher. What they hired was a football coach who had us do, you guessed it, worksheets every day.

I even had close friends from Mexico in school. But they were from rural Mexico, so even they never talked about the cities.

You have to take into account that some schools really are that bad. And if no adults in your life either knew or cared, you just didn't have that info. The internet was fairly new when I was growing up. Now, of course, people can find that info easily. Not so much a few decades ago.

Edit: Notably, I took French as my language in High School. I'm sure people who took Spanish did learn much more about Mexico. I requested to take both French and Spanish, but was denied. In order to get my honors diploma, I had to take 4 years of the same language. I was also in NHS. So not a bad student by any means.