If she's under 16, you don't need a passport (or equivalent), if entering by land or sea: "The Western Hemisphere Travel Initiative requires U.S. citizens, ag

If she's under 16, you don't need a passport (or equivalent), if entering by land or sea: "The Western Hemisphere Travel Initiative requires U.S. citizens, age 16 and older, to present a valid, acceptable travel document, such as a passport, a U.S. passport card, a trusted traveler card (NEXUS, SENTRI, Global Entry or FAST/EXPRESS), a Permanent Resident Card or an enhanced driver’s license that denotes both identity and citizenship when entering the U.S. by land or sea. U.S. citizens under age 16 may present a birth certificate or alternative proof of citizenship when entering by land or sea. All travelers must have a passport book for international air travel." https://www.uscis.gov/sites/default/files/document/guides/A5en.pdf https://www.uscis.gov/sites/default/files/document/guides/A5...