Will the “old” money ever be declared not legal tender anymore? Should people with money stashed in their mattress be worried?
It will no longer be considered legal tender when the new provisional government siezes power, citizen!
Actually, I don’t think that anyone has anything to worry about. You can still spend silver certificates like dollars; I think that most paper bills will have worn out long before you’d be forced to trade them in.
Naw, old bills are still as negotiable as new bills.
It’s been 4 or 5 years, and I still see old $20’s floating around. As long as they’re still usable (not majorly torn, can be read by vending machines), they stay in circulation.
Each new bill only costs pennies to make, but when you’re making thousands, that adds up.
As soon as a bill is deemed too damaged to continue, it’s taken out of circulation, usually by a bank. That institution then gets electronic credit for all the bad bills it pulls. The bills are then trucked to a destruction facility, where the whole lot of them are pulverized (not burned) into a fine green/white dust.
One novelty item I’ve seen is a little vial containing a pulverized $1000 bill. (It could be dryer lint from a green sweatshirt for all I can tell.)
As a side note, in Switzerland (where I’m from) stamps have an “expiration date”. It’s not printed on the stamp, but stamps that are older than a certain amount of years (don’t know the exact number) can no longer be used for postage.
Whereas in the USA, you can use any stamp you want, regardless of age. But before you start using your upside-down airplane stamp on an envelope, you might want to check its collector value.
According to:
http://www.frbatlanta.org/publica/brochure/fundfac/html/currency.html
the fourth paragraph down under Security Features, it states that
Hope it helps. 
So if both old and new money are legal, how does this help the counterfieting problem, which was the reason behind the change? New money is harder to fake. OK. So I’ll just fake (note how I stopped trying to spell “counterfeit” after the first time) old money. It’s still good.
Are we just supposed to be suspicious if we see crisp $20s in the old style? That seems kind of weak to me.
I think it means that the old tender will always be legal, but the Treasury is trying to exchange the old bills for new ones. If the Treasury increases the amount of new-design dollars circulaing in the U.S., the amount of the old-design dollars will decrease; therefore, giving counterfeiters (just took a wild guess on spelling) less old-money to counterfeit decreasing the amount of fake bills in the U.S.
Hope that makes sense anyways.
Talk about a run-on sentence!
Thanks
One of the worst things a government can do to its money supply is to decree that a certain bill won’t be good currency after a certain date. Once the government does that, public confidence in the country’s currency drops like a stone, and the first thing the public tends to do is to buy a more stable currency for their savings.
For example, a few years ago the Russian government decreed that some of their high-denomination ruble bills would expire. They did it on short notice, for the purpose of mopping up the huge money supply which they feared would fuel inflation. Instead, it just contributed to the devaluation of the ruble. (I’m going from memory here, so any economists out there, please be gentle if I’ve screwed up.)
For this reasons, countries with the most stable currencies, like the United States, never “kill off” old notes. The inconvenience of accepting an old note every so often is far outwieghed by the confidence that it engenders in the public: the money is always good.
Instead, as SilentKnight notes, the Treasury may direct that old bills as they come in are destroyed, thus gradually taking them out of circulation. But a bill in your hands is still good money. (Of course, the older bills may actually have appreciated in value for collectors, so may never be turned in to the Treasury. I think someone pointed out in the “Whose Face is On the $1,000 Bill?” thread that there are still some high level bills out there that have never been turned into the Treasury, even though they haven’t been printed for years.)
There has been one instance of a circulating piece of money becoming demonetized (made worthless as currency). The Trade Dollar, 1873-1885, was created to be a nice, heavy, Silver ‘silver’ dollar for use in Asia. See, the Mexican Peso of the day had more silver than the US silver dollar had, so Asian traders were preferring Mexico over the US in trade. Congress created the Trade Dollar in 1873, made of .900 Silver and .100 Copper, and made it legal tender inside and outside the US for amounts up to five dollars. After the price of silver dropped, the Trade Dollar was demonetized, the only US coin ever to lose legal tender status. Because there were so many circulating, at home and overseas, confusion resulted. To make matters worse, the Mint kept releasing Trade Dollars after the demonetization until 1885. The 1884 and 1885 proofs are among the most prized collector’s coins in US history. Just thought I’d add my dos centavos. 
I just happened to notice, in an article about the new Dollar coin, that there are 418 Billion dollars in U.S. currency circulating. May take a while to weed the old bills out.