I've been quiet too long...
So, I'll just quote the CIA World Fact book:
The US has the largest and most technologically powerful economy in the world, with a per capita GDP of $46,000. In this market-oriented economy, private individuals and business firms make most of the decisions, and the federal and state governments buy needed goods and services predominantly in the private marketplace. US business firms enjoy greater flexibility than their counterparts in Western Europe and Japan in decisions to expand capital plant, to lay off surplus workers, and to develop new products. At the same time, they face higher barriers to enter their rivals' home markets than foreign firms face entering US markets. US firms are at or near the forefront in technological advances, especially in computers and in medical, aerospace, and military equipment; their advantage has narrowed since the end of World War II. The onrush of technology largely explains the gradual development of a "two-tier labor market" in which those at the bottom lack the education and the professional/technical skills of those at the top and, more and more, fail to get
comparable pay raises, health insurance coverage, and other benefits. Since 1975, practically all the gains in household income have gone to the top 20% of households. The response to the terrorist attacks of 11 September 2001 showed the remarkable resilience of the economy. The war in March-April 2003 between a US-led coalition and Iraq, and the subsequent occupation of Iraq, required major shifts in national resources to the military. The rise in GDP in 2004-07 was undergirded by substantial gains in labor productivity. Hurricane Katrina caused extensive damage in the Gulf Coast region in August 2005, but had a small impact on overall GDP growth for the year. Soaring oil prices in 2005-2007 threatened inflation and unemployment, yet the economy continued to grow through year-end 2007. Imported oil accounts for about two-thirds of US consumption. Long-term problems include inadequate investment in economic infrastructure, rapidly rising medical and pension costs of an aging population, sizable trade and budget deficits, and stagnation of family income in the lower economic groups. The merchandise trade deficit reached a record $847 billion in 2007. Together, these problems caused a marked reduction in the value and status of the dollar worldwide in 2007.