It is easy to look down the slope of this trend and predict the end of paper currency. Easy, but probably wrong. Most Americans prefer to use cash at least some of the time, and even those who do not, like Mr. Zazula, grudgingly concede they cannot live without it.
Currency remains the best available technology for paying baby sitters and tipping bellhops. Many small businesses — estimates range from one-third to half — won’t accept plastic. And criminals prefer cash. Whitey Bulger, the Boston gangster who lived in Santa Monica for 15 years, paid his rent in cash, and stashed thousands of dollars in his apartment walls. Indeed, cash remains so pervasive, and the pace of change so slow, that Ron Shevlin, an analyst with the Boston research firm Aite Group, recently calculated that Americans would still be using paper currency in 200 years. “Cash works for us,” Mr. Shevlin said. “The downward trend is clear, but change advocates always overestimate how quickly these things will happen.”