A consent letter is recommended for all cross-border travel, even for a day trip, if the child will be travelling alone, with only one parent, with friends or relatives or with a youth group.
While the US does not legally require a parental consent form, US Customs and Border Protection strongly recommends one. Here's the advice from their Web site, bolding mine:
Is a minor travel consent form required for domestic travel? No, a minor travel consent form is not required for domestic travel within the U.S. However, it is recommended that parents and/or legal guardians carry a notarized letter of consent when traveling with a child.
You should obtain a child travel consent letter granting you permission from the absent parent to leave the country with your child (having it notarized is not required, but highly recommended).
Date: DD/MM/YYYY I have no objection in sending my child _______________________________________studying in Class _______& Section ______ for the field trip/picnic/event to ___________________________ _____________________(place) on ___________________(date(s) of the picnic/field trip/event).
The traveling parent will need to carry a Child Travel Consent form (also known as a Permission to Travel Letter, Minor Consent to Travel, or Parental Consent to Travel form).
Typically, minors under the age of 18 do not have to present identification for domestic U.S. travel. Airlines will accept identification from the responsible adult on behalf of the minor(s). For international travel, minors under the age of 18 must present the same travel documents as the adult.
How to fill out the Travel Consent Form for Minor Child - Parent Authorization? Enter the parent's name and relationship to the child. Provide the child's full name and date of birth. Input the details of the accompanying adult. Specify the travel dates and destinations. Sign the form as the consenting parent.
Custody and out-of-state travel in Arizona often require obtaining consent from the other parent, especially if there is a joint custody agreement. If there is a sole custody arrangement, the custodial parent usually has more flexibility but must still consider any court orders or restrictions.
A consent letter is recommended for all cross-border travel, even for a day trip, if the child will be travelling alone, with only one parent, with friends or relatives or with a youth group.