Britain's American colonies broke with the mother country in 1776 and were recognized as the new nation of the United States of America following the Treaty of Paris in 1783. During the 19th and 20th centuries, 37 new states were added to the original 13 as the nation expanded across the North American continent and acquired a number of overseas possessions. The two most traumatic experiences in the nation's history were the Civil War (1861-65), in which a northern Union of states defeated a secessionist Confederacy of 11 southern slave states, and the Great Depression of the 1930s, an economic downturn during which about a quarter of the labor force lost its jobs. Buoyed by victories in World Wars I and II and the end of the Cold War in 1991, the US remains the world's most powerful nation state. Since the end of World War II, the economy has achieved relatively steady growth, low unemployment and inflation, and rapid advances in technology.
The US has the most technologically powerful economy in the world, with a per capita GDP of $57,300. US firms are at or near the forefront in technological advances, especially in computers, pharmaceuticals, and medical, aerospace, and military equipment; however, their advantage has narrowed since the end of World War II. Based on a comparison of GDP measured at purchasing power parity conversion rates, the US economy in 2014, having stood as the largest in the world for more than a century, slipped into second place behind China, which has more than tripled the US growth rate for each year of the past four decades.In the US, 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, businesses face higher barriers to enter their rivals' home markets than foreign firms face entering US markets.Long-term problems for the US include stagnation of wages for lower-income families, inadequate investment in deteriorating infrastructure, rapidly rising medical and pension costs of an aging population, energy shortages, and sizable current account and budget deficits.The onrush of technology has been a driving factor in 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. But the globalization of trade, and especially the rise of low-wage producers such as China, has put additional downward pressure on wages and upward pressure on the return to capital. Since 1975, practically all the gains in household income have gone to the top 20% of households. Since 1996, dividends and capital gains have grown faster than wages or any other category of after-tax income.Imported oil accounts for nearly 55% of US consumption and oil has a major impact on the overall health of the economy. Crude oil prices doubled between 2001 and 2006, the year home prices peaked; higher gasoline prices ate into consumers' budgets and many individuals fell behind in their mortgage payments. Oil prices climbed another 50% between 2006 and 2008, and bank foreclosures more than doubled in the same period. Besides dampening the housing market, soaring oil prices caused a drop in the value of the dollar and a deterioration in the US merchandise trade deficit, which peaked at $840 billion in 2008. Because the US economy is energy-intensive, falling oil prices since 2013 have alleviated many of the problems the earlier increases had created.The sub-prime mortgage crisis, falling home prices, investment bank failures, tight credit, and the global economic downturn pushed the US into a recession by mid-2008. GDP contracted until the third quarter of 2009, making this the deepest and longest downturn since the Great Depression. To help stabilize financial markets, the US Congress established a $700 billion Troubled Asset Relief Program (TARP) in October 2008. The government used some of these funds to purchase equity in US banks and industrial corporations, much of which had been returned to the government by early 2011. In January 2009, Congress passed and President Barack OBAMA signed a bill providing an additional $787 billion fiscal stimulus to be used over 10 years - two-thirds on additional spending and one-third on tax cuts - to create jobs and to help the economy recover. In 2010 and 2011, the federal budget deficit reached nearly 9% of GDP. In 2012, the Federal Government reduced the growth of spending and the deficit shrank to 7.6% of GDP. US revenues from taxes and other sources are lower, as a percentage of GDP, than those of most other countries.Wars in Iraq and Afghanistan required major shifts in national resources from civilian to military purposes and contributed to the growth of the budget deficit and public debt. Through 2014, the direct costs of the wars totaled more than $1.5 trillion, according to US Government figures.In March 2010, President OBAMA signed into law the Patient Protection and Affordable Care Act, a health insurance reform that was designed to extend coverage to an additional 32 million Americans by 2016, through private health insurance for the general population and Medicaid for the impoverished. Total spending on healthcare - public plus private - rose from 9.0% of GDP in 1980 to 17.9% in 2010.In July 2010, the president signed the DODD-FRANK Wall Street Reform and Consumer Protection Act, a law designed to promote financial stability by protecting consumers from financial abuses, ending taxpayer bailouts of financial firms, dealing with troubled banks that are "too big to fail," and improving accountability and transparency in the financial system - in particular, by requiring certain financial derivatives to be traded in markets that are subject to government regulation and oversight.In December 2012, the Federal Reserve Board (Fed) announced plans to purchase $85 billion per month of mortgage-backed and Treasury securities in an effort to hold down long-term interest rates, and to keep short-term rates near zero until unemployment dropped below 6.5% or inflation rose above 2.5%. In late 2013, the Fed announced that it would begin scaling back long-term bond purchases to $75 billion per month in January 2014 and further reduce them as conditions warranted; the Fed ended the purchases during the summer of 2014. In 2014, the unemployment rate dropped to 6.2%, and continued to fall to 5.5% by mid-2015, the lowest rate of joblessness since before the global recession began; inflation stood at 1.7%, and public debt as a share of GDP continued to decline, following several years of increases. In December 2015, the Fed raised its target for the benchmark federal funds rate by 0.25%, the first increase since the recession began. With US GDP growth below 2%, the Fed has opted to raise rates three times since then, and in mid-June 2017, the range for the target rate stood at 1% to 1.25%.