The bills and coins in your pocket are an interest-free loan to the government that produced them anyway. With actual interest rates around zero for much of the past 16 years, demand boomed, especially outside the U.S., for $100 bills, the easiest denomination to store but the hardest one to spend. There are now more of them in existence than ubiquitous $1 bills. The response to a future financial crisis could well be negative interest rateseven in the U.S. It isn't just digital money that makes that more likely. During the Great Depression, when slashing rates didn't revive the economy, the problem was described as "pushing on a string." The solution was for the government to give people money to spend