nothing - but you will need a U.S. authorized document to get back into the U.S.
It is advisable to have a passport but a citizen of Mexico or the USA can do this with a drivers license.
Mexico
walk north
you can drive there or fly there walk there
about how long would it take to walk from east Texas coast to Mexico citey
about how long would it take to walk from east Texas coast to Mexico citey
Only if you have a valid ID or birth certificate.
Take a Car, a Bus, a plane or walk across the border.
Two months
To cross INTO Mexico, you need...nothing. You just walk or drive through. However, in order to get OUT of Mexico, you need a U.S Passport and it's always a good idea to carry around some form of identification, just in case.
Yes, you need a valid passport for a flight to Mexico.
Yes, you can walk across the bridge that connects El Paso to Ciudad Juarez.