Passport arrived yesterday

English: Specimen of the U.S. passport card, i...

I received my passport yesterday. I received a card as well that allows me to go to Canada, Mexico and some other places. It was interesting because it looked like a driver’s license. It said it needed to be protected in a case that was provided due to being “sensitive electronics.” That doesn’t sound like an advantage to me of having that system. The Passport book isn’t sensitive electronics.

So it got me to thinking what I am supposed to do with the old passport that they sent back to me. Any ideas? I shredded it. Didn’t want to risk someone using it.