I recently posted on a currency shortage in Argentina (and previously on a similar problem in Guatemala); George Selgin addresses the same topic in today's WSJ. A snip:

Suppose you want to ride the bus or feed a parking meter without exact change. Or suppose you just want to drop a few cents in a street musician's hat. Nothing easier, right? Not if you live in Argentina. Try doing any of these things there, and you could be in for a major hassle.

Why? Because Argentina is in the grips of a small-change shortage. Want change for a five-peso (about $1.70) note? Don't try getting it at a store, unless you plan to buy something -- and be ready in that case to have the merchant refuse your business rather than part with precious centavos, or to have him hand you bon-bons instead of coins. Banks aren't much help either. The law says they're supposed to give you up to 20 pesos worth of change; but most openly flout that rule, supplying just a few pesos worth, or even hanging out "No Change" signs, like the ones at retailers' kiosks.

Why the shortage? Argentina's central bank blames it on "speculators," meaning everyone from ordinary citizens, who stockpile coins, to Maco, the private cash-transport company (think of Brinks) that repackages change gathered from bus companies to resell at an 8% premium. But those explanations ring false. "Black marketeering" would not exist if coins were easy to get in the first place. After all, Argentines could just as easily hoard razor blades or matchbooks. Yet there's no shortage of those. What's so special about coins?

The answer is that coins are supplied by the government alone. "Put the federal government in charge of the Sahara desert," Milton Friedman said, "and in five years there'd be a sand shortage." If Argentina wants to end the coin shortage, it ought to give up its monopoly.