In the past 20 years, the GAO, Congress' investigative arm, has issued four recommendations for a switch to metal dollars in order to save all the money spent to replace worn-out dollar bills. Dollar bills last longer than they used to and now have a life span of up to 40 months. But the coins have an average life span of 30 years. http://www.aolnews.com/2011/03/07/us-wants-to-take-your-dollars-and-replace-them-with-coins/
