Is there any reason why US money used to be only three colors?

Yeah I know about the the yelowback currency and the beautiful rose colored designs on the Canal Bank of New Orleans banknotes, but all and all at least 99% of US money has been black, green and red (and occasionally brown). Is there any reason?

Intaglio printing process and limited suitable inks.

There is no technical reason why the USA shouldn’t move to a modern secure printing technology: it might even be a good idea: I understand that there are few forged banknotes in the USA, but many forged USA banknotes outside the USA.

But historically secure inks were not available in most colors, and most inks weren’t suitable for intaglio printing.

For a long time the seal on Silver certificates was blue.

Obviously the government has to use special inks for printing money…it was once called “secret ink,” according to a long-forgotten source.

Maybe the OP is really looking for the reason why US money has traditionally been the same color for all denominations. The US is the only country (as far as I know) in which currency denominations are not color-coded, to simplify the recognition of them. In addition, most countries also print their banknotes in different sizes. France, for example, printed money that was so colorful that there was no discernible color motif, but the largest bills had to be folded up like road maps to fit in pockets or wallets.

They aren’t all the same color any more, although since many of the denominations have some shade of green near the corners, it’s hard to convince some people of this. There was a thread some time back where a Canadian was complaining that our money was still all green. I tried to convince her otherwise, but to no avail.

Somewhere I read that the specific shade of green found on older bills and still on the $1 and $2 notes was difficult for counterfeiters to reproduce when first introduced. But that was back in the 1800s and no longer applies.

If it is “hard to convince” people who use the currency every day, then, for practical purposes, they are all still perceived as being green. And color is what you perceive it to be .

The backs are all green, within a fairly narrow range of green shading, except for an occasional figure in another color. The paper may be slightly tinted in some denominations. The fronts are mostly gray/black impressions, again with some insignificant color printing.

I always hear that, but I can’t say that it’s ever been terribly confusing to have money that’s the same size and color. They do print the denomination in the corners pretty prominently.

By contrast, I’ve had issues in other countries with larger bills obscuring smaller ones.

I don’t have a real opinion about the color coding; I never spent long enough in any other country to really get to where the colors were intuitive. I always have had to read the denomination, regardless of the size or color.

Are you blind or vision-impaired? I understand that varying the size and colour of the bills (or using tactile features, such as raised dots) can help such people immensely.

I remember reading something a while ago (20 to 25 years ago) that some US government people were worried that the public would not like a radical redesign of the currency, and would equate a rainbow of brightly colored bills as “funny money”. People might not believe that it’s real American money at first - hence the slow and gradual approach to adding color to the bills, just making minor changes. The fact that the dollar coins got limited acceptance probably doesn’t help their case.

But it wasn’t money she used every day. This was a Canadian and she only used it on occasional visits to the states. To double check, I asked a person who did use is every day – in fact that was his job, since he was a bank teller. He agreed with me that the notes were all distinctive colors and he had no problem distinguishing them. Much better than the old all-green bills.

I kind of thought tradition since so much currency throughout US history has been black, red and green.

I wonder what method other countries use? There’s an imperial Russian 10,000 ruble note that looks like the designer went insane in a dye factory.

A number of foreign countries (Australia, NZ, UK, most recently Canada) have switched to a polymer currency - with transparent sections, holographic images - it is much harder to fake than something that just needs good paper and a colour printer to fool the average non-critical recipient. beyond that, of course, all banknotes take advantage of the need for extreme resolution. High colour simply adds to the complexity since precise colour reproduction (both hue and saturation) is still tricky without high-tech equipment.