The new bills, which go into circulation early next year, are the same size and colour as those in use since 1929. But they contain an array of instantly recognisable new features to defeat the ever more sophisticated scanner, copier and printer technology at the disposal of the modern counterfeiter.
On the 1996 series $100 bills, the familiar portrait of Ben Franklin is enlarged and moves off-centre to the left. Like the revamped $50, $20 and smaller denominations to be introduced over the next few years, the banknote will for the first time have a watermark, colour-shifting ink, and fine-line concentric patterns too intricate for current scanners to resolve.
Almost certainly, the changes will have less of an impact in the US (where credit cards and cash machines have turned the $100 bill into something of a rarity) than abroad, where no less than two-thirds of the current $380bn US note-issue circulates, and where most of the counterfeiting takes place.
In scores of countries, starting with Russia and the former Soviet states, dollars operate in parallel to domestic currency.