The United States is the world’s largest national economy in nominal terms and second largest according to purchasing power parity (PPP), representing 22% of nominal global GDP and 17% of gross world product (GWP). The United States‘ GDP was estimated to be $17.914 trillion as of Q2 2015.
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 US 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.
The United States has a mixed economy and has maintained a stable overall GDP growth rate, a moderate unemployment rate, and high levels of research and capital investment. Its seven largest trading partners are Canada, China, Mexico, Japan, Germany, South Korea, and the United Kingdom. The US has abundant natural resources, a well-developed infrastructure, and high productivity. It has the world’s ninth-highest per capita GDP (nominal) and tenth-highest per capita GDP (PPP) as of 2013. 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.