The US has never won an official game in the Azteca (although they won a friendly 1-0 last year), and the stadium has become a house of horrors for the Americans since the USA-Mexico rivalry really heated up in the last ~30 years.
The Azteca holds 100,000 fans, and it's architecture is such the sound funnels down from the rafters onto the field. The high altitude and poor air quality also contribute to the hostile environment.
Here's what it's like on the field when Mexico scores a goal:
The moment the US team walked out of the tunnel and onto the field to start the game:
And here's when they came out for warm-ups and the boos rained down: