It's normal in Tijuana to know someone born in San Diego or someone whose children were born there, but live in Mexico. If you cross the border often with your child or a minor, you must know what the officers might ask you.

According to information from CBP, if a parent decides to travel with their child, he or she must have a note from the other parent. If he or she travels with a family member or a group, then the letter must be written and signed by both parents.

If a minor is younger than 18 years old and travels with one of their parents, grandparents, siblings, uncle or aunts, or a legal tutor, the adult must carry a signed letter by both parents.

I acknowledge my wife/husband/etc. is traveling outside of the country with my child/daughter/son. He/she/they has/have my permission.

American citizens younger than 19 years old traveling by land or sea from Mexico and travel with a school, religious or sport group, they must present an original copy of their birth certificate, a Consular Report of Birth, or a naturalization certificate. Meanwhile, the group must have a letter of official letterhead with the following information:

● The children's names on the trip and their primary address, phone number, date and
place of birth, and name of at least a parent or legal tutor per child.
● The name of the group and the supervisor adult(s) like: school groups, adolescent visits, vacation groups
● A written and signed declaration of a supervising adult that certifies he or her has
consent from the parent or legal tutor per child. CBP also suggest that this note is
notarized, to easily verify the validity of the parent's authorization.

For those frequent cross-borders, the letter must not exceed a year and it is recommended to be written in English.

CBP officers may not ask for this document when crossing, however, if they do and you don't have it, they may detain you until they evaluate the child's circumstances of traveling without both parents.

Vía CBP