Bus to Mexico City Airport?

[roberb7]

The Yellow Line is generally much less crowded than the rest of the Metro, because it doesn't go downtown.
There's a major exception to this, however; December 11-12, the day before and the day of the Virgen de Guadalupe. One of the main pilgrimage routes is the Circuito Interior, which goes right by the airport, and the Yellow Line runs parallel to it. And, if you take a bus or taxi during this period, it will be painfully slow going. So, the best thing to do is, mark these two days on your calendar, and don't book any flights to or from MEX on them.
If you ignore this wise piece of advice, you'll be sorry.