Is a money in any form when in US. The united states of America Dollar has become the mostly recognized and acceptable medium of exchange when you travel around the world and most currencies are below the dollar. Valuation of currency is determined by the demand for it just like the demand for goods and services. US dollar is much protected and the country may even force you to value its own currency higher if it detects devaluation. Do you think that United states of America always wants to have advantage over other nations and have its name praised?

