Live animals, toxic substances, explosives, any kind of unregistered or illegal drugs, fruits and vegetables, any kind of uncanned food.
From the US? It is international travel. If you mean NEW Mexico, that is domestic travel, though.
Actually, it is more likely to catch the H1N1 in America than in Mexico. You should take that shot even if you are not traveling to Mexico soon.
You mean from the US? It is international.
Texas, New Mexico, and Arizona.
Your birth certificate will not help you. You can enter the US from Mexico with an "enhanced" US drivers license, but only if you are traveling by sea or land, not by air.
If you're flying to New Mexico from outside the US then yes. If you're traveling to a New Mexico airport from some other airport in the US you should not need it, though if you are not a US citizen it would probably be a good idea for you to have your passport with you anytime you're traveling within the US anyway.
Mexico city was taken
The US census is taken nationwide every ten years, those years that end in 0.
Through the Mexican-American War (1846-1848) most of New Mexico was taken from Mexico. Later, during the Gadsden Purchase (1853) Mexico sold the southern part of New Mexico.
Yes, you do.
None.
No. To enter Mexico from the US you would need your American passport. If you don't, you would require an ID or birth certificate when traveling by land.