I recently renewed my passport, and have a shiny new one. When renewing, I sent in the old one as proof of citizenship/identity, but was surprised that, along with my new passport, the old one was sent back - with a few holes punched in it to verify it's 'uselessness'.
Most advice I can find re: holding on to expired passports mainly advises doing so in order to use them for the exact purpose that I used mine; but beyond that (since I have a new passport, which will someday be expired), is there any reason to hold on to the old one? If not, are there any particular precautions I should take in disposing of it beyond ensuring that the page with my identity is torn out and shredded/cut into tiny pieces to avoid identity theft?
(If it's relevant, mine is a US passport)