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.
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.
Some facts about the USA:
Population 316 million
Area 9.8 million sq km (3.8 million sq miles)
Major language English
Major religion Christianity
Life expectancy 76 years (men), 81 years (women)
Currency US dollar
President: Donald Trump
Republican candidate Donald Trump defeated Democratic candidate Hillary Clinton to win the presidency in the 2016 election. Mr Trump's victory was one of the biggest upsets in US political history, confounding the opinion polls and putting an end to eight years of Democratic control of the White House.
A billionaire businessman, reality TV star and political outsider, Mr Trump campaigned on a vow to "make America great again".
