IIRC, the US has never declared any version of its old currency not-legal-tender, and no-one would have any problem spending any US banknote that in any way resembles the current ones in size or shape.

They do. Mainly to track banknote usage and average life from when / where they enter circulation, to when / where they end up. Basically demand for and lifecycle of cash. It is valuable information for knowing how much to print, and for improving the durability of notes themselves (which is surprisingly low, an average of months, with a non-fat long-tail to weeks, for low denomination notes).

[BTW, the date on the note has little to no relationship to the date it enters circulation, the serial number is used for this.]

That's not so impressive when the National Bank of Sweden for instance is legally obliged to exchange any banknotes it issued for current ones, regardless of their age. You can theoretically get current money in exchange for a 17th century obligation or certificate issued by the bank, though even early 20th century notes are worth more as collection items than their nominal value.

https://www.uscurrency.gov/denominations/bank-note-identifie...

Technically, $500, $5000, and $10000 also exist in private collections. They were last printed in 1945, and stopped being issued in 1969. They're worth far more than their denomination to collectors, understandably.

Also, technically, $100k bills exist. They, however, were printed during the Great Depression and intended solely for transfers between federal reserve banks, and were never circulated. It's illegal to hold them privately, though there are some museums and things that have one.

It takes a while for all the old bills to get out of circulation though -- a few years ago I got my hands on a $20 bill from 1970 and the kid at the corner store almost didn't take it since they had apparently never seen one that old, probably didn't help it was nice and crisp as well. Only thing I can imagine is someone was saving it from their birth year and had to spend it for whatever reason since $20 in 1970 was over $100 in today's dollars so they lost a bunch of value holding that bill.

Our money (US Currency) has two (of the same) serial numbers on each bill; one on the lower left and one on the upper right for dollar bills. Other denominations also have two; one on each side of the front of the bill, however they are in opposite places i.e. upper left, and lower right--at least the current bills in my wallet are that way.

I fear we are headed this way even in the U.S. For decades, I've been holding within my residence some for-emergency-use currency in $20s, $50s, and $100s, but am now slowly replacing all my older Benjamins ($100s) with newer ones I get from the ATM every 4-6 weeks. I haven't had much problem spending the older ones (I guess higher prices means making change isn't such a burden for retailers anymore), but they do often get more scrutiny, testing with the special pen, etc.

Apparently, how money works in most places but not in the US... I can't imagine it would be very controversial however, if US authorities announced that "in 10 years, banknotes older than the 1960's will be invalid, you can exchange them for new notes before that". Why would it be controversial? It would be a big change after having so old money being legal tender, but it would be understandable not least because old money without modern features is likely much easier to counterfeit than new.

In any case: banknotes expiring completely or being made invalid/replaced by new editions with the same denomination isn't anything strange, even if it would be news in the US. So in that light, removing some denominations of Euro notes wouldn't be controversial. Remember: all the EU countries already quite recently had ALL their original banknotes made invalid (after period of conversion, which I believe has ended a long time ago in the original EUR-countries).

Well, they do have different numbers on them. Different pictures too. I find them easy to distinguish at a glance.

Most money (specifically, most US dollars) are not in the form of coins or notes. See: https://www.quora.com/How-many-dollars-are-there

~1.4 Trillion USD in notes ~60 Trillion USD total

coins are certainly less than notes, but I'm not sure how much less, so let's guesstimate no more than 0.5 Trillion, and that's a stretch. So, about 97% of money is not in notes and coins.

Generally speaking you have to take it, within a certain point of reason.

I will say that in my time in retail, I've seen 50s or 100s that looked 'weird' to me but after a pen/light check looked fine. The choke point is somewhere between a hot wash and a high heat dry of the bill; it just starts to look (shrunken/grainish)/feel (too fibrous) off. The older a bill is (unless it's one of those 'special saved for a long time bills', but sometimes those look off because of how pristine they are) the more likely it will be to have gone through one of these events.

That said, we always would at minimum marker-check anything over 20$, even if it was a semi-lazy 'sweep' over a small portion.

Of course, if I was ever questioned by a customer, I'd give some polite fiction (educating people about the Eurion Constellation is a fun diversion!) or some education on why. Optionally, if it was a customer I'd know really well, (I had a few of those) I'd try to play 'psychic' and guess what laundry settings the bill went through. Those folks usually enjoyed the learning experience about decay of currency (I have a type I guess.)

EDIT:

I'll also add, I'm guessing the Argentina black market probably has a lower ability to detect 'supernotes'; i.e. counterfeit notes created by an organization that has the resources of a (possibly adversarial) government with sufficient resources and funding. IIRC some of the older 100$ notes were among those known to be impacted.

Yeah, that's how they are, but feeling like they're going to fall apart and actually falling appart are two different things.

> Though your $20 notes are usually in excellent condition for some reason compared to the british equivalent.

$20 bills tend to get picked up at the bank, spent at a merchant, and deposited at a bank. Banks will send worn notes to be retired. Many businesses don't take bills larger than $20, so don't use $20s to make change. It's uncommon to pay vendors and employees in cash, so merchants end up with a surplus of $20s that need to be deposited.

$1 bills are used in change, so they tend to get exchanged frequently. Few consumers will deal with $1s at a bank, and many businesses won't ever deposit them, but may need to make withdrawls in $1s so they can make change. They tend to pass through many hands before they get back to a bank where their condition can be checked.

No they don’t. Nobody records the serial numbers of each bill the receive and pass and who they got it from and gave it to in a publicly accessible ledger.

The article seems to be a bit coy about this. It says that the notes

> can’t be swapped for cash at a bank

but doesn't, I guess, rule out other means of conversion.

What are you talking about?

> the issuing authority usually puts and end date to the old version a few years into the future

Not in the US.

It depends on the denomination. I think $1s have a lifetimes of ~18 months, but it goes up from there. I would imagine $100s have useful lifetimes of at least a decade if not more.

I quite like that and never really understood why US bills are only green. If I look for 50€ in my wallet, I’m going to skip over the blues and greens and essentially directly pick the right orang-y one.

I’ve also never seen anyone suspicious of 50€, people sometimes look funny if they see 100€, but even that happens rarely.