Do U.S. citizens need a passport to go to Mexico and back?To be absolutely exact, depends.
The minimum required nowadays for travel to Mexico (and the Caribbean, Canada and Bermud) and back via land or sea is a passport card. Apparently one can enter Mexico by air with the passport card, but upon return to the US (via air) a passport is required.
Eligibility requirements for both passport and passport card are the same (being a US citizen) but the card is cheaper.
If you walk across or drive across the border, you will not need a passport to enter Mexico, but the US requires everyone, including US citizens to show a passport when entering the US. If you fly into an international airport in Mexico, you will need a passport. Mexicans do not need a passport to enter or leave Mexico, but they do need identification that verifies their nationality.
Yes, a passport is the accepted option to cross the border. Particularly US immigration is careful about people crossing from Mexico having proper paperwork; a driving license for example doesn't indicate you are a US Citizen or permanent resident
According to a U.S. agent at the U.S./Mexico border at Tijuana a few months ago:
(1) U.S. citizens are required to show a passport upon crossing back into the U.S.
(2) U.S. citizens cannot legally be excluded from entering the U.S. regardless of whether they have a passport or not.
Yes. Once upon a time children could travel with a notarized affidavit from both of those parents, but those days are gone. Americans need a passport to travel to both Mexico and Canada, regardless of how far into the country you want to go.