Consider this, the first US 100 dollar bill note was issued in 1862 and the version that you know now, the Federal Reserve note featuring the US founding Father Benjamin Franklin on the foreside,  was actually launched in 1914. This means that if your great, great, great grandfather happened to bury a chest full of US100 dollar bills since then, you could still today unearth it and the bill would be accepted as legal tender i.e. the same bill note is still in circulation today. 

 Well not quite but you get the idea.  Actually, the US100 dollar bill that is used today came into circulation on July 13, 1969 and as of December 2018, the average life of a $100 bill in circulation is approximately 30 years before it is replaced due to wear.