As long as it is domestic travel (within the U.S.) children do not need ID as long as they are traveling with an adult who can present ID. If the child is traveling alone and does not have an adult who can present a valid ID at check-in, then the child will need to provide ID. Any Government issued form of ID should suffice. I would recommend checking with the airline to be sure. This answer applies to air travel only.
Not unless you are the driver.
your id
I'm not sure about an id for travel within the United States. A Passport is for international travel only, you will not need one if you fly to any of the 50 US states
Yes, but you will need some government issued photo id (Driver's license, etc).
No - ID will be OK - but it is sensible to carry with you anyway
This will depend on where you want to travel. If only within US then you need a valid ID, if international travel you need you passport, visa and other requirements like immunization and such.
He/She will need an ID of some sort, but not specifically a passport.
There are a couple of answers for you but no matter what you need an ID for all answers I'm about to give. If you travel by bus, or any automotive you need a U.S. Naturalization Citizenship document and if you travel by plane or boat you need a passport POSTER: In response to your question. So, if you are a U.S. citizen, once you are actually in the country of Mexico, you still need to provide ID to go from one part of Mexico to another? What if you are a Mexican citizen who ONLY wants to travel within the borders of Mexico. Would he need an ID?
well its a good idea to have your valid Driver's license or State ID on you, but to travel within the U.S., you are not required to have any documentation.
yes
Passports are usually just for international travel and are not necessary for domestic travel. You may need some kind of ID while traveling within a country.