At the beginning of the 19th century, Britain was the world's superpower. By the end of the 20th it was America.
The transition was preceded by two world wars. Some time this century, the balance of power will change again. Mr. Obama has inherited a world of pressing troubles. But as he tackles them, he will need to keep an eye on the longer game; how to prepare for the day when America may no longer be the sole superpower and only the first or second of many big powers. To manage that transition peacefully and still promote the spread of free markets and liberal democracy: that will be the mark of a truly great president for the 21st century.
-The Economist
