A passport card is valid for all domestic flights, as well as land travel to Canada and Mexico. I prefer it to my passport book when appropriate as it's sturdie

A passport card is valid for all domestic flights, as well as land travel to Canada and Mexico. I prefer it to my passport book when appropriate as it's sturdier and easier to carry. It's also nice on international trips as proof of U.S. citizenship (though you'll usually need your book at border crossings)