So much of America's power comes from its size: it is one the largest countries on Earth by population and area, and is rich in natural resources and human capital. It is also in many ways an island nation; because it faces no major threats on its borders, it is freer to project power globally.

There was no reason that North America's borders had to become what they are. A key moment in how that happened came with the French and Indian War, at the time just a sideshow in the larger Seven Years' War in Europe. The war ended with France giving up its vast territory on the continent to Britain and Spain. Napoleon would seize back Louisiana and sell it to the US in 1803, but New France was lost forever. With the Spanish Empire already declining, the continent was left open to conquest from the British Empire and its successor, the United States.

Image credit: University of Maine