If a U.S. minor less than 18 years old wants to enter Canada without parents, she must carry a letter of permission to travel to Canada, signed by both parents. The letter should be notarized.
Minors under 15 traveling with or without parents and children 16 to 18 traveling in school groups may carry proof of citizenship without a photo ID, but only if crossing the land border into Canada. This could be in the form of an original birth certificate or naturalization papers.
Kids traveling by air are required to show the same ID as adults: a passport book, passport card or NEXUS card.
Bring legal custody papers if you're a divorced parent traveling with your kids to prove you're not taking them away from the other parent.
