The economy of the United States remains the world's largest national and second overall largest world economy with the GDP of the European Union being $ 2 trillion larger in terms of USD. Nominal GDP for the U.S. was estimated to be $15.8 trillion in 2012, comprising nearly a quarter of total world nominal GDP. At purchasing power parity, the U.S. economy is the largest in the world, and represents one-fifth of the total sum of PPP worldwide.

The U.S. is well known for its mixed economy sustained by reserves of abundant natural resources, well-developed infrastructure and high rate of productivity. Its four largest export trading partners are Canada, China, Mexico and Japan.

About 60% of global currency reserves are comprised of U.S. dollars, compared to 24% investment in the Euro. Foreign investments in the U.S. total almost $2.4 trillion and 133 of the world's top 500 countries are headquartered on U.S. soil.

The United States' economy is also affected by the economic downturn that has stagnated markets worldwide as part of the global recession of the late 2000's. Unemployment is still above historic trends as of 2012, but is lower than rates first seen at the onset of the crisis. The U.S. also lost its AAA credit rating because of this economic stagnation and the political fallout that ensued.