We've all desperately tried to force a crumpled dollar bill into a vending machine to no avail. Fortunately, when your dollar is that decrepit, it's on death's door and will likely be removed from circulation.
The average lifespan of a $1 bill, according to the Federal Reserve Bank of New York, is 21 months. Eventually, money is destroyed — either by the Federal Reserve itself, or by the places that create it to begin with: the Bureau of Engraving and Printing, and the U.S. Mint. On average, 5 million unfit currency notes are destroyed each day.