I’m sure the question has been asked before, but searching returned a gazillion answers.
In most countries that I’ve been, and in my own, bills are different size and color. One reason is to help the vision impaired sort it all out. Of course I find it more convenient and whenever I visit the US, I always have to read the bill to know if it’s a five or a twenty. If you’re born and raised with it, I’m sure it’s natural.
So why did the US take this course?
They aren’t, anymore. Haven’t you seen the new US 20’s?
Just a WAG, but it was probably cheaper at the get-go - less ink, same size plates, etc., and we just haven’t seen fit to change things since then.
More FYI:
I’ve just looked at the new 20, thanks. Nice looking, though still a bit greenish in color.
But this is for 2004. It’s been the old way for, well how long? And Why.
From the above link:
“NEW YORK CITY – October 9, 2003 – The most secure currency in U.S. history was introduced into the economy today, as a newly redesigned, colorful $20 bill was issued by the Federal Reserve System.”
IIRC, less than a week after the new “peachies” debuted, counterfeit bills started appearing (cannot find cite).
Perhaps the counterfeit peachies lacked the appropriate fuzz compared to the real ones.
My understanding is the new colors are fairly subtle so how helpful is that to a visually impaired person?
The colors on the new $20 aren’t that subtle. It’s pretty obvious that the new 20s are a different color.
And I’d imagine bills have been the same size and color to save money. You only have to buy green and black ink, and all the machinery can be used to print and cut all the bills. If the $20 were bigger than the $5, you’d either need another machine to cut it, or have to retool the machine each time you wanted it to cut a differently sized bill
counterfeit bills showing up already
And some ATMs and money counting machines are rejecting the genuine bills as counterfeit. Guess the Feds forgot to notify the banks.
The new bills might not be all that hard to reproduce after all.
Save money… bleh. It’s not like we don’t print out a zillion of the things a year, they can probably retool the line once or twice without breaking the bank.
I think it’s because we’ve ‘always done it this way’, that and Americans are notoriously stodgy and wouldn’t like ‘funny colored’ bills.
For example, they won’t go for a completely sensible dollar coin, or any other alteration of our currency system. We have jars at home to collect essentially worthless coins, so that when we finally have enough to bother with, we can pay a machine to count them for us. But, imply that you want to get rid of the penny, and you get all sorts of resistance.
At the quantity the Feds print money, I doubt if they are using just one cutting machine, and I doubt if buying another one would be a problem (they can just print the money to purchase it, right? 
)
While diff sizes of bills could be helpful to the sensory-impared, think of the mess it would make in your wallet.
I don’t understand why the new Sacajawea dollar coin has so many people’s panties in a wad. This is not the Susan B Anthony quarter, after all. It’s a different color than any other coin, for starters. It’s a different size too, though close to a quarter’s. But it lacks the quarter’s ridged edge, so you can tell instantly by feel in your pocket what it is. It’s big and has smooth edges, so it’s a dollar. As opposed to a dollar bill, which gets ratty and needs replacing after an avg. of 17 months, the coins last 40 years or more, saving the taxpayers millions.
Maybe there are some folks who recoil at the notion of gasp a woman on a coin–and holding her mixed-heritage child, no less.
For me it has to do with how much of my money I take out of circulation. Dollar bills go back in my wallet to be used later; coins (except quarters – those’re for laundry) get dumped into a jar that takes the better part of a year to fill. By keeping the dollars around I get to delay going to the MAC machine for a couple days, but don’t get a big payoff at the end of the year. Using dollar coins would eventually produce the same net effect, but I wouldn’t want to “sit on” several hundred dollars while I wait for the jar to fill.
I think it was more because
It was new…everybody’s used to the dollar bill
It was never widely put into service…everybody who got one said, “Hey, this is the first one of these I ever saw” and held onto it.
It’s a coin, which translates to “just one more piece of junk in my pocket.”
In fact, different coloration has, at times, been present in US bills. For instance, a lot of the “gold certificate” currency of the late 19th century show a lot of variation in coloring:
http://www.currencygallery.org/large/lgc.htm
A lot of those bills had red or yellow backs. One interesting group of US bills was the series 1896 “educational” series, which showed allegorical figures:
http://www.currencygallery.org/large/lsc1896.htm
The 1896 series was apparently not well accepted because people felt that their money should “look like money, not racy French playing cards”, referring to the artsy scantily clad female figures in the allegories. So they went back to sticking the ugly mugs of various politicians on the bills. And Martha Washington, whose mug wasn’t all that good looking either.
People tend to be very conservative about the appearance of their money, and gripe whenever it is changed in any way. The difference in the US seems to be that the BEP puts more stock in the gripes. A lot of countries recognize that people will adapt, and just make the changes, letting them gripe for a few months.
Personally, I wouldn’t mind different colors, but I WOULD gripe about them being different sizes. That would making thumbing through the bills in my wallet a real hassle.
Face it - the only way you will get people to use dollar coins is to quit printing dollar bills. There’s sort of a mutant of Gresham’s law at work here - more convenient money formats drive out the less convenient. People simply wish to pay for purchases with a large bill rather than bothering to make change, and building up a stack of dollar bills to carry around is less onerous than carrying around a pocketful of coins. This would be true if you put Sacajawea, some dead president, Saint Francis of Assisi or Mickey Mouse on the coins. It would be true if they were milled, non-milled, perfectly round silver, or 31-sided gold colored polygons.
I realize that this is somewhat subjective, and that reasonable people can differ, but I was about to post agreement with World Eater: I do think the color difference on the new $20’s is pretty subtle. 
Holding old and new bills side-by-side, the difference was certainly visible, but it did not jump out at me. I was disappointed, frankly.
I think it’s still a far cry from the bright reds, greens, blues, and yellows that I’ve seen in many non-US currencies.
I would go crazy if they decided to make bills in different sizes. How would you ever keep them neatly folded in your wallet?
You’re not implying that only good-looking people should be on money, are you? Or that we should only elect politicians who are good-looking and have good-looking wives?
Money is money. It should do the job. Looks are secondary.
You won’t get people to change with this statements like that.
About how many people have their “panties in a wad” over this? Can you quote any figures?
There are some, no doubt. But do you seriously contend that sexism and racism is a significant factor in not using the Sacky?
I don’t get this. You might as well say, how do you keep your coins neatly stacked if they’re not all the same size? Unless you’re checking your million-dollar bribe for fakes, you don’t need to flip through your bills like a deck of cards. And if you order them smallest to largest, it’s actually much easier to see what’s in a stack of different-sized bills than same-sized ones. Different colors help with this too.
I think that we Americans oppose accessibility measures in currency because we hate handicapped people. 