ARO-HEALING

The USA is the world's foremost economic and military power, with global interests and an unmatched global reach.

America's gross domestic product accounts for close to a quarter of the world total, and its military budget is reckoned to be almost as much as the rest of the world's defence spending put together.

The country is also a major source of entertainment: American TV, Hollywood films, jazz, blues, rock and rap music are primary ingredients in global popular culture.

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The United States originated in a revolution which separated it from the British Crown. The constitution, drafted in 1787, established a federal system with a division of powers which has remained unchanged in form since its inception.

The US contains a highly diverse population, the product of numerous and sustained waves of immigration. Ethnic and racial diversity - the "melting pot" - is celebrated as a core element of the American ideology.

The 1964 Civil Rights Act outlawed racial and other discrimination, but race continues to be a live issue.

The election of Barack Obama as the country's first African-American president in November 2008 marked a defining moment in the country's chequered history of race relations.

Freedom and prosperity

The original people of north America, who made up several distinct groups of native Americans, went into decline with the arrival of settlers and now constitute a minority of the population.

The early settlers came predominantly from the British Isles. Large numbers of black Africans were taken as slaves to work the plantations of the Americas, while millions of Europeans in search of political freedom and economic opportunity constituted a third stage of immigration.

Today, Asians from the Pacific rim and Hispanics from the southern Americas are among those seeking what their predecessors wanted - the promise of prosperity and freedom which remains one of the defining hallmarks of "the American dream".

Despite relative prosperity in recent years, the gap between rich and poor remains a major challenge. More than 30 million Americans live below the official poverty line, with a disproportionate percentage of these being African-Americans and Hispanics.

Furthermore, the global financial crisis of 2008 has left the US facing its most challenging set of economic circumstances since the Great Depression of the 1930s.

9/11 aftermath

The terrorist attacks of September 11 2001 had a momentous impact as the country continued to re-define its role as the world's only superpower.

In October 2001 the US led a military campaign in Afghanistan which unseated the Taleban regime. However, the man thought to have inspired the 9/11 attacks, Al-Qaeda leader Osama Bin Laden escaped the operation and eluded the US until 2011, when killed in a US special forces operation in Pakistan.

In March 2003 Washington initiated military action in Iraq which led to the toppling of the Iraqi leader Saddam Hussein.

US foreign policy has often mixed the idealism of its "mission" to spread democracy with the pursuit of national self-interest.

Given America's leading role on the international stage, its foreign policy aims and actions are likely to remain the subject of heated debate and criticism, as well as praise.

Democratic Senator Barack Obama was elected the first black president of the United States in an historic election win in November 2008.

His emphatic victory over his opponent John McCain, who struggled in vain to distance himself from the unpopular presidency of George W. Bush, ended eight years of Republican rule in the White House.

Mr Obama clinched the Democratic Party's nomination in June 2008, following a long and bruising primary race with former first lady and fellow Democratic senator, Hillary Clinton.

He ran for president on a ticket promising change, and came to office riding a wave of high expectations from his supporters, both at home and abroad.

President Obama inherited a formidable in-tray of problems from Mr Bush. The US was facing its worst economic crisis since the Great Depression of the 1930s, and his administration the task of determining the next steps in the lingering conflicts in Iraq and Afghanistan.

He made reform of the healthcare system to extend coverage and reduce ballooning costs one of his top domestic priorities.

Despite a tortuous drafting process and vociferous Republican opposition, Mr Obama and Democrats in Congress finally succeeded in passing a health care bill in March 2010.

However, the health reform, along with the $787bn stimulus package passed in February 2010 to shore up an ailing economy, galvanised opposition among some Americans to Mr Obama's agenda.

The American Right in particular worries about what it sees as moves to extend the role of the state in the economy, and the threat of excessive public debt.

The rise of the conservative Tea Party movement in 2009 re-energised the Republicans and helped them to capitalise on popular discontent at the slow pace of America's economic recovery.

The Republicans made sweeping gains in mid-term elections in November 2010, regaining control of the House of Representatives.

The mid-term election result represented a serious setback for Mr Obama, as with his opponents controlling the House the president is likely to find it much harder to turn his plans into laws.