Yes the US is the most powerful country in the world... on paper. The piece of paper that the US prints money to say is one dollar can also be used to say it's a hundred dollars...
Most powerful because of military size? I would say that only matters when you're able to translate military power to influence.
They have an incredibly bloated gdp from non productive finance and housing sector bubbles, yet still doesn't reach up to China.
Real power comes from control over goods and logistics. US has done well in commercial airlines, but that makes up only a fraction of global logistics. If you more closely examine the American empire, I don't even believe the US mainland is the most powerful entity within their empire, let alone globally. Japan and SK are.
See, SK, Japan make up 95%+ of the US Empire's shipbuilding, and also 90%+ of their semiconductor production. Without them, US would not be able to ship goods, and also not make the electronics needed to build anything advanced, including weapons. Mainland USA might be the government seat, but SK and Japan are the spice mines keeping the whole empire's logistics and production possible.