You will need a passport if you are traveling by airplane. This is because international treaties on air travel state that all passengers and crew boarding an international flight must carry a valid passport booklet.
If you are traveling by boat (Cancun is a popular cruise destination), then you can get away with a passport card or "enhanced" drivers license. Crossing the US-Mexican border is also possible on foot or in a motor vehicle with only a US passport card or "enhanced" drivers license. There are no trains that cross the US-Mexican border.
Yes, you need a valid passport to travel to Cancun by air.
Yes, a passport is required to travel to Cancun in 2016.
Yes. Whenever you enter another country by air, you need a passport.
Yes, you need your passport.
just your passport
yes you do. you need a passport to fly anywhere outside of the United States.
Yes. All you need is your passport and means of payment.
You always need a passport to enter another country
If entering Mexico via airplane, yes.
No, I have never visited Cancun and received a passport stamp as a souvenir.
No, it is not possible to fly from Tijuana to Cancun without a passport. A valid passport is required for all international flights within Mexico.
No, unless you are stopping at the US.