What would happen if the USA de-valued its currency on purpose to increase its exports?

R B asked:


China lowers the international value of its currency so that its exports are super-cheap! The USA used to have currency backed by gold (see the Bretton Woods Agreements) but now market fundamentals MAY finally be catching up with the USA. (Maybe. Maybe not.) Exporting more than we import would certainly help the economy in the long term.