How long should a boarding pass be preserved, after the trip? Is there any FAA mandate on the same to make any claims later? Ok, i'm not sure if this is relevant to AviationSE, but my query is as a passenger.

How long should a passenger preserve their boarding pass after their trip? This is with view for making any kind of claim on the Airline, be it for lost luggage, or injury during the trip, or any thing else. Is there any relevant FAA guideline or rule on the same?
If you have arrived approximately in time, picked-up your undamaged luggage, passed immigration and customs and doesn't want to use an airtrain (or something similiar) you should be able to safely discard it.  

Personally I tend to keep them as holiday memory, so I miss the old style tickets/boarding-passes from the 90ies :)