In hidden vaults across the country, the US government is building a stockpile of $1 coins. The hoard has topped $1.1bn – imagine a stack of coins reaching almost seven times higher than the International Space Station – and the piles have grown so large the US Federal Reserve is running out of storage space.
Americans won't use the coins, preferring $1 notes. But the US keeps minting them anyway, and the Fed estimates it already has enough $1 coins to last the next 10 years.
And at the current rate, the inventory will grow to $2bn (£1.3bn) by 2016, the Fed estimates.
The coins began to pile up in 2007 when a law went into effect creating a new series of $1 coins commemorating dead US presidents.