Counterfeiting has existed for centuries, with coins commonly counterfeited by clipping edges and melting them together in the 1600s. Currently, most paper currency counterfeits are made by scanning and printing bills or combining pieces of legitimate bills. In 2010, $64.4 million in counterfeits were in circulation in the US due to economic hardship increasing incentives. Detecting counterfeits involves checking security features like ridges, ink smearing when rubbed, watermarks, and thickness. Producing counterfeits was historically punishable by death and remains a serious federal felony today.