UPDATED 2022: You NO longer need the form for the following airports.
If you are flying IN and OUT of the following airports:
Cancun International Airport (CUN)
Cozumel International Airport (CZM)
Los Cabos International Airport (SJD)
Puerto Vallarta International Airport (PVR)
Mexico City International Airport (MEX)
You NO longer need to fill out the Forma Migratoria Multiple (FMM) also known as Tourist Card for the above-Listed airports for US Citizens.

There are a few exceptions:
If you are flying to/from ANY OTHER airport in Mexico NOT listed above, then you may still need to fill out the Immigration Form "manually" when you arrive or depart from another airport in Mexico.
If you are visiting from a country that requires a visitor VISA, then you still need to fill out the form. Please be aware that for the airports listed ABOVE you will need to fill out the form "manually" upon your arrival to Mexico.
If you are NOT a "visitor," for example, a permanent resident in Mexico, then you still need to follow the normal arrival procedures as before.
Here's the official link to the form: [ Ссылка ]

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