Minors age 15 and under must have proper identification, such as a birth certificate, passport, citizenship card, permanent resident card or Certificate of Aboriginal Status. While passports are recommended, they are not required for American minors age 15 or younger crossing the border by land - a birth certificate will suffice.
If a minor is travelling alone or with an adult that is not their parent or guardian, they should carry a letter from their parents/ guardians. This letter should authorize the person meeting them or travelling with them to take responsibility for the minor while visiting Canada. The letter should also include addresses and telephone numbers where the parents or guardian can be reached.
Divorced or separated parents should carry custody or legal separation documents and a letter of authorization from the other parent to facilitate their entry into Canada.
If you are travelling with a group of vehicles, make sure you arrive at the border in the same vehicle as your children, to avoid any confusion.