The United States is a highly developed/advanced mixed economy. It is the world's largest economy by nominal GDP, and the second-largest by purchasing power parity (PPP) behind China. It has the world's seventh-highest per capita GDP (nominal) and the eighth-highest per capita GDP (PPP) as of 2022. The U.S. accounted for 25.4% of the global economy in 2022 in nominal terms, and around 15.6% in PPP terms. The U.S. dollar is the currency of record most used in international transactions and is the world's 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.
The American economy is fueled by high productivity, transportation infrastructure, and extensive natural resources. Americans have the highest average household and employee income among OECD member states. In 2021, they had the highest median household income. The U.S. has one of the world's highest income inequalities among the developed countries. The largest U.S. trading partners are Canada, Mexico, 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.
By 1890, the United States had overtaken the British Empire as the world's most productive economy. It is the world's largest producer of petroleum and natural gas. In 2016, it was the world's largest trading country as well as its third-largest manufacturer, representing a fifth of the global manufacturing output. The U.S. not only has the largest internal market for goods, but also dominates the services trade. U.S. total trade amounted to $4.2trillion in 2018. Of the world's 500 largest companies, 121 are headquartered in the U.