A dollar weighs one gramme, according to the U.S. Bureau of Engraving and Printing. The weight of a US note is the same for all denominations.
There are 454 notes in a pound because there are 454 grammes in a pound. According to the Bureau, these currency notes are also strong enough to resist 4,000 double folds before tearing and are made of 75% cotton and 25% linen.
The ink on the notes is green, which indicates strong and stable credit and is particularly chemically resistant. The $100,000 banknote, which was only ever used for Federal Reserve operations in the 1930s, was the highest note ever printed.