$300 million for coins nobody wants

American taxpayers could save $500 million (£312 million) a year if they switched from paper dollars, which wear out quickly and must be replaced, to the more durable metal version, according to the US government accountability office.

Yet demand from banks for the coins has been so low that $1.2 billion (£749 million) worth – which cost $300 million (£187 million) to manufacture – are sitting in storage, an investigation by National Public Radio found.

Opinion polls show that three-quarters of the American public say they would prefer to carry on using the paper dollar bill, affectionately known as the “greenback”, which celebrates its 150th birthday next year.