I was looking through Wikipedia and found my way to the Boxer Rebellion and noticed the US was one of the allies among the other great powers of the time. Japan was a member but was not considered a power until the Russo Japanese war.
However, I wondered when was the US considered a great power. Was it after the Civil War or before when the US annexed the much of the West coast?
I know the US was considered a superpower following WW2 so my thinking is wars are what usually pushes a country to that level of influence.
And bonus question. Did the British ever felt threatened by America's rise as they happened to be so close and shared a similar culture and historical ties?
This is going to vary depending on who you ask.
I would argue that the US became a formidable World Power at the end of WW1, when it had proven itself on the world stage (at least in terms of industrial output), and military ability.
World war 2 however was what really really made the US a superpower. The war hadn't really touched the US in the same way it did Europe or Japan, the US didn't need to rebuild, it still had the massive industrial output it had accumulated during and before the war. The US was the de facto last man standing, giving it a lot of power in the international stage.