Do you need a passport to get into mexico?

http://travel.state.gov/travel/cbpmc/cbpmc_2223.html

In short, not yet; however, it's a good idea.

I went to the Mex. I got the recommended Tourist Visa. You're not really supposed to need the Passport but the customs guard asked for it & luckily we hads it. Let alone it's handy for returning Norte.

There's alot of "technical" crap in the law; it's better to have the passport. E.g. Technically in alot of countries, Canada included, the customs officer /can/ still technically accept an oral declaration of citizenship (though that hole is being plugged). In practice, passport or bust.

No but you'll need one to get out.