What determines which bills are taken out of circulation; time, date or wear?

serpa

Wear. In the US. How is U.S. currency destroyed when it is removed from circulation? Currency processing and authentication machines at Federal Reserve Bank cash offices determine whether the currency received from circulation is genuine and fit for recirculation. If a note is genuine but too worn for recirculation, the note is shredded. The shredded notes are sent to landfills or packaged and provided as souvenirs to the public during tours of the Federal Reserve Banks. How long does a bill last before it wears out? $ 1 21 months $ 5 16 months $ 10 18 months $ 20 24 months $ 50 55 months $100 89 months http://www.federalreserve.gov/generalinfo/faq/faqcur.htm#1 Apr 02 10, 1:06 PM