International use of the U.S. dollar in the context of "USD"

The United States dollar (symbol: $; currency code: USD) is the official currency of the United States and several other countries. The Coinage Act of 1792 introduced the U.S. dollar at par with the Spanish silver dollar, divided it into 100 cents, and authorized the minting of coins denominated in dollars and cents. U.S. banknotes are issued in the form of Federal Reserve Notes, popularly called greenbacks due to their predominantly green color.

The U.S. dollar was originally defined under a bimetallic standard of 371.25 grains (24.057 g) (0.7734375 troy ounces) fine silver or, from 1834, 23.22 grains (1.505 g) fine gold, or $20.67 per troy ounce. The Gold Standard Act of 1900 linked the dollar solely to gold. From 1934, its equivalence to gold was revised to $35 per troy ounce. In 1971 all links to gold were repealed. The U.S. dollar became an important international reserve currency after the First World War, and displaced the pound sterling as the world's primary reserve currency by the Bretton Woods Agreement towards the end of the Second World War. The dollar is the most widely used currency in international transactions, and a free-floating currency. It is also the official currency in several countries and the de facto currency in many others, with Federal Reserve Notes (and, in a few cases, U.S. coins) used in circulation.

The United States has a highly developed diversified market-oriented mixed economy. It is the world's largest economy by nominal GDP and second largest by purchasing power parity (PPP). As of 2025, it has the world's ninth-highest nominal GDP per capita and eleventh-highest GDP per capita by PPP. According to the World Bank, the U.S. accounted for 14.8% of the global aggregate GDP in 2024 in purchasing power parity terms and 26.2% in nominal terms. The U.S. dollar is the currency most used in international transactions and the world's foremost reserve currency, backed by a large U.S. treasuries market, its role as the reference standard for the petrodollar system, and its linked eurodollar. Several countries use it as their official currency and in others it is the de facto currency. Since the end of World War II, the economy has achieved relatively steady growth, low unemployment and inflation, and rapid advances in technology.

The American economy is fueled by high productivity, well-developed transportation infrastructure, and extensive natural resources. Americans have the sixth highest average household and employee income among OECD member states. In 2021, they had the highest median household income among OECD countries, although the country also had one of the world's highest income inequalities among the developed countries. The largest U.S. trading partners are Mexico, Canada, China, Japan, Germany, South Korea, the United Kingdom, Taiwan, India, and Vietnam. The U.S. is the world's largest importer and second-largest exporter. It has free trade agreements with several countries, including Canada and Mexico (through the USMCA), Australia, South Korea, Israel, and several others that are in effect or under negotiation. The U.S. has a highly flexible labor market, where the industry adheres to a hire-and-fire policy, and job security is relatively low. Among OECD nations, the U.S. has a highly efficient social security system; social expenditure stood at roughly 30% of GDP.