Coming into USA with only birth certificate?

He is supposed to take the documents to a U.S. embassy or consulate with his parents, apply for a passport, and enter the U.S. with the passport.

First of all, his parents are citizens of Mexico? Then they need to verify he is a Mexican citizen as he holds birthright citizenship in Mexico by birth to Mexican citizens. That establishes that he is & has been legally residing in Mexico, and is not an illegal alien.

Due to the very high incidence levels of child-identity theft, it is entirely possible that the birth certificate he has is not & never was his. So there will have to be investigation & verification of that birth certificate before he might be issued a US passport. If he was a genuine US-born citizen, his parents had to get him a US passport before leaving US as US citizens are required to enter/exit US only on US passport. Penalties apply for failure to do so. His parents got him into Mexico somehow, e.g. proving they were Mexican citizens bringing in their Mexican-citizen child.

It sounds simple: use US birth certificate to apply for US passport. It is not as simple as it sounds due to the child-identity theft issue and the lack of supporting documentation. Since he is a minor, both parents must attend him in person, with their proof they are his parents, for him to apply for a passport.

Also, as a minor child, he cannot travel internationally without his parents, nor can he live on his own. IF he can prove he is a genuine US-born citizen, and obtains a US passport, he can travel alone after he turns 18, when he will be old enough to work without restrictions under state child labor laws, legally sign contracts such as a lease to get a place to live, etc.

He needs to use that ID to obtain his US passport via a US Consulate in Mexico (where he'll need his parents' cooperation because he's a minor).

He needs a US passport. To apply he has to make an appointment at the nearest US Consulate and at least one of his parents needs to go with him to the appointment.

https://travel.state.gov/content/travel/en/passpor...

He needs a passport

He would need a US passport.

Contact the US Embassy and request a passport. I don't know enough about US law to know if he'll get his own passport or have to travel under his parent's.

Are his parents American? That makes it easier.