<Tr> <Th> Foreign reserves </Th> <Td> $125.076 billion (March 2, 2018) </Td> </Tr> <Tr> <Td_colspan="2"> Main data source: CIA World Fact Book All values, unless otherwise stated, are in US dollars . </Td> </Tr> <P> The economy of the United States is a highly developed mixed economy . It is the world's largest economy by nominal GDP and the second - largest by purchasing power parity (PPP). It has the world's seventh - highest per capita GDP (nominal) and eleventh - highest per capita GDP (PPP) in 2016 . The U.S. dollar is the currency most used in international transactions and is the world's foremost reserve currency, backed by its science and technology, its military, the full faith of the U.S. government to reimburse its debts, its central role in a range of international institutions since World War II and the petrodollar system . Several countries use it as their official currency, and in many others it is the de facto currency . Its largest trading partners are China, Canada, Mexico, Japan, Germany, South Korea, United Kingdom, France, India and Taiwan . </P> <P> The U.S. economy is fueled by abundant natural resources, a well - developed infrastructure, and high productivity . It has the second - highest - total - estimated value of natural resources, valued at $45 trillion in 2016 . Americans have the highest average household and employee income among OECD nations, and in 2010 had the fourth - highest median household income, down from second - highest in 2007 . It has been the world's largest national economy (not including colonial empires) since at least the 1890s . The U.S. is the world's third - largest producer of oil and natural gas . In 2016, it was the largest trading nation in the world as well as the world's second - largest manufacturer, representing a fifth of the global manufacturing output . The U.S. also has not only the largest economy, but also the largest industrial sector, at 2005 prices according to the UNCTAD . The U.S. not only has the largest internal market for goods, but also dominates the trade in services . U.S. total trade amounted to $4.92 trillion in 2016 . Of the world's 500 largest companies, 134 are headquartered in the US . </P>

The united states is an example of what type of economy