Sometimes pennies can be more trouble than they're worth. While a 1909 penny could send a postcard or buy a few eggs, in 2009 it can't even purchase itself: the U.S. Mint spends 1.4 cents on every penny it produces. "When people start leaving a monetary unit at the cash register for the next customer, that unit is too small to be useful," argued Harvard economics professor Gregory Mankiw in a 2006 Wall Street Journal article. Arizona representative Jim Kolbe introduced the 2002 Legal Tender Modernization Act to Congress, which would have eliminated the penny. The bill failed miserably.