They may require age verification depending on the ticket type. I believe TSA says "no" for security, but Southwest may say "yes" depending on the ticket type for Child Fare, or as an infant < 2 y.o. https://www.tsa.gov/travel/security-screening/identification https://www.southwest.com/html/customer-service/family/children-pol.html For our <2 y.o. lap baby we do bring a copy of a birth certificate for proof of age.
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