Fiber

• U.S. currency paper is made of a special blend of 25 percent cotton and 75 percent linen fibers, unlike normal paper, which is made of wood fiber. Red and blue fibers are added to the paper for extra security.
  
  

Security thread

• Special security threads are woven into the paper for security. These threads are printed with the bill's denomination number--like "USA 100" for a $100 bill. This prevents counterfeiters from bleaching the money and reprinting it with a higher denomination.
  
  

Watermarks

• Watermarks are an ancient technique for preventing counterfeits. The watermark is built into the paper and is created by variations of density in the fiber. They can only be seen when the paper is held up to light.
  
  

Life Span

• The average life span of a U.S. $1 bill is 21 months. When money is worn out, it is removed from circulation and destroyed.
  
  

Fun Fact

• Before World War I, the fibers used to make U.S. currency paper were silk.
  
  

History

• In ancient times, many different items were used as money: seashells, beads, coins and even stamped leather. The first paper money was used in China in the ninth century.