The US has the largest economy in the world. Measured in terms of contemporary exchange rates, 2014 US GDP was about $7 trillion higher than the second largest economy, China.
Indeed, the US economy is so large that the state economies that cumulatively make up the national economy are themselves comparable to other countries.
America's stock markets are correspondingly huge. The August 2015 market capitalizations of the two main US exchanges — the New York Stock Exchange and the NASDAQ — dwarf the rest of the world.
Seven of the ten largest companies in the world by market capitalization, and all of the top five companies, are American.
The dollar remains the most important reserve currency in the world, as can be seen by the IMF's breakdown of Q2 2015 foreign reserve holdings by currency.
America is moving towards energy independence. After peaking in 2006, US crude oil imports have steadily dropped, largely owing to the domestic shale oil boom.
America is also dominant in scientific research output, publishing the most scientific papers of any country in the world in 2014.
Nine of the ten highest grossing movies of all time are unambiguously American.
"Harry Potter" has a lot of British people involved, so we'll give that one to them.