Although it was not always necessary, currently (as of January 2012), yes it is necessary. UNLESS you are a frequent traveller or live in a contiguous border state, then there are special ID cards issued which can take the place of a US Passport.
From Another Country to Mexico most likely yes. As far as I know as long as you are crossing a border for a country you need one.
Whether or not you need a passport to travel to anywhere outside the U.S. or U.S. territories, you need a passport to return to the U.S. Homeland Swcurity you know.
Yes you will need a passport. For details, references, and links, please also see "Do you need a passport to travel from the US to Mexico?".
Yes, a US passport is required for all International travel.
no if you are flying from a state in Mexico to another state in Mexico
you don't need one
Yes, if you are from a country other than Mexico.
It depends on your nationality
Yes, you will need to catch a plane to go to Cabo San Lucas if you live in Australia. You can't do it by car, because there is water between Cabo San Lucas and Australia.
Your passport
Your passport
If you are goning to Mexico or Canada you need a passport.
No, but you will need a passport to get back into the US.
Yes, you need a passport to go from the U.S. to Mexico because Mexico is not part of the U.S. If you were going to a U.S. territory and you were a U.S. citizen, you would not need a passport.
No. New Mexico is part of the United States, so you don't need a passport. :)
It is advisable to have a passport but a citizen of Mexico or the USA can do this with a drivers license.
Yes. All you need is a passport.
If you live in Mexico then no.
does a citizen of Mexico need a passport to go from the us to Mexico and back? He is legal to be in us but not a us citizen.
You always need a passport to enter another country