You're SUPPOSED to turn over all old/unwanted cash to the Treasury dept. so they can officially remove it from circulation and destroy. But I'd image no one is enforcing that too seriously.
I think it is illegal, but not terribly enforceable. I wouldn't want to throw it out, though. If you take your unwanted bills, coins to the bank, they'll give you newer bills for it or trade your coins in for cash. Do you really want to throw money away?
If you need a place to discard your old cash, let me send you my snail mail address! I did find out (the hard way, again) that it is ILLEGAL to take money out of circulation as in putting into a safety deposit box. I don't see how that can be enforced...and what's the difference between a S.D. box and under the mattress?
With gas prices the way they are, I’d keep every penny I find. I walked around the block and found 5 dollars from people that just throw money down or drop it. It all adds up. I agree with gooch too.
If it is ILLEGAL to take money out of circulation, then how do you explain the US Mint selling coins for collectors, or the fact that coin shows aren’t raided?
Well one destroys it in the Penny and Quarter machines, but for a price. I like penny pressings. But I went to take my pennies in to the bank today (came up around $8.47) which actually might save me an overdraft charge. But pennies that the bank machine doesn’t count I guess are thrown directly in the trash o_O , always thought banks, especially banks would send them back to the treasury dept to be destroyed. Guess not. :(