I am Mexican and only have a Mexican passport, but I am also an American citizen. I was wondering if I needed to have an American passport to travel from Austin to Guadalajara (roundtrip) or is ok with my Mexican passport?
By law, American citizens are restricted from using other nationality documents to enter the US.
Therefore, you cannot - as a US citizen, enter the US with your Mexican passport.
Here are the list of documents accepted for entry from US citizens by the CBP as listed on their website. If you are carrying any of these, then you can use them to enter the US.
Air Travel: All U.S. citizens departing from or entering the United States from within the Western Hemisphere by air are required to present a valid passport or NEXUS card (if utilizing a NEXUS kiosk when departing from a designated Canadian airport). Merchant Mariner Document (for U.S. citizens on official maritime business.) U.S. Military identification card when traveling on official orders; Note that children are also required to present their own passport when traveling by air.
Land or Sea Travel: U.S. citizens entering the United States by land or sea are required to present a valid WHTI-compliant document, which include:
- U.S. Passports
- U.S. Passport Cards
- Enhanced Driver's Licenses
- Trusted Traveler Cards (Global Entry*, NEXUS, SENTRI, or FAST)
- Military Identification Cards (for members of the U.S. armed forces on official orders)
- U.S. Merchant Mariner Document (for U.S. citizens on official maritime business)