As of June 1, 2009 U.S. and Canadian citizens under the age of 16, or under the age of 19 if traveling with a school, religious or other youth group, may present a birth certificate, Consular Report of Birth Abroad, Canadian Citizenship Card, or a naturalization certificate. Birth certificates can be an original, photocopy, or certified copy.
More information can be obtained at www.GetYouHome.gov