I don’t want to go into a big long thesis so I’ll try to summize.

America, now firmly cemented in its boarders, fully federalised and with a wealth of natural resources and ballooning population was becoming a big power by the start of the 20th century and American politicians were putting in considerable effort into undermining the big European powers, but especially Britain.

The British empire being so spread out made it hard to defend and control. So with Britain and it’s colonies fighting on every front for the whole length of the war Britain lost many colonial holdings in Asia.

Those colonies also paid a heavy price in the fighting and independent movements flourished after the war and Britain didn’t have the money or political will the fight them, so the empire dissolved.

America was able to use its war economy to massively ramp up its domestic manufacturing.

They were also able to use their position as financers and occupiers in Europe and Asia to extend considerable American influence to those regions. And also Latin America and the Caribbean. Giving American companies influence over much of the world without the obligations the British Empire had.

While everyone is talking about World War II, it is kind of important to discuss what led the USA to become capable of taking over.

First, the USA was a giant as a successor nation to American colonization. It had significant natural resources, a relatively easily navigable interior, and a budding industrial sector. Unlike Spanish colonies, the USA had pretty good national institutions where wealth could be created.

After the War of 1812, the UK had already shifted its strategic approach to the USA. The UK would allow the USA to be a local hegemon as long as the USA respected existing British colonial claims. This led to the Monroe Doctrine, partially enforced by the UK. There were also a lot of cases where the UK chose not to press claims to antagonize the USA. This included a peaceful solution to the Oregon Territory crisis and not participating in the French invasion of Mexico.

The USA was considered to be a rising great power by the end of the 19th century, including destroying the remnants of the Spanish Empire. Many nations recognized that the USA benefited from the same geographical features that the UK did, with the homeland being far removed from any other competing power.

The USA could have credibly become the leading great power after World War I had the USA not chosen to go into isolation after the war. By then, it was apparent that the USA had a military and economy to be a major international player, but the US Republican Party didn’t want to agree to the international commitments.

So, by the end of World War II, the USA was already the preminent economic power for at least a generation. The USA was then able to build a military capable of fighting a two front war while supplying many of its allies in the war. Meanwhile, the UK was seeing its empire fall apart and knew it couldn’t afford to be the international leader. Choosing between the USA and USSR, the UK chose the USA.

Because we came out on top at the end of WWII, but we were the main Allied nation whose country didn’t get blown to smithereens during the war due to being an ocean away. (Granted, neither was Australia but they were not and did not become a manufacturing powerhouse in the process.)

All of the European colonial powers lost a ton of their colonies either during or in the immediate aftermath of the second world war, especially the British empire. Australia is even included in that list, becoming independent in 1942. The rest looks like a who’s-who of former British colonies and protectorates, the most impactful and arguably the most famous being India in 1947. Also Jordan (1946), Myanmar/Burma (1948), Sri Lanka (1948), Israel (carved out of the British mandate of Palestine, also 1948), and many others in the intervening decades.

The Brits had to dedicate most of their military forces to fighting the war which left their various colonies undermanned. India’s independence in particular put into motion the expectation that all of these lands and protectorates could self-determine, and since Britain was A) broke, and B) imperialism was becoming progressively less socially acceptable in Europe, Britain let most of them go. Not least of which because they did not have the manpower to spend keeping those pesky natives down, nor did they have the money to spend paying anyone to do so for them.

America, meanwhile, built huge swathes of industrial capacity during the war which was all still there afterwards, owned significant amounts of debt from the various European powers from loans made and equipment provided before we entered the war fully, essentially owned Japan for a decade or two, and importantly did not suffer any damage to its own infrastructure, factories, or civilian populations due to being separated from both theaters of war by an entire ocean each.

TL;DR: Pretty much everyone involved in the war was left with a country made of rubble and ashes in varying degrees, except the US.

Because that was the deal for them to choose sides during WW2, now they’re at the end of that deal.

The UK just about lost and probably would have if the US didn’t get fully involved, and the big kid on the block need help and then the helper became the leader.

Which country is next, every empire collapses.

There’s a host of factors, I’ll try to outline the ones I can think off off the top of my head

1. Industrial base: The UK was bombed during WWII, the US was not. That gave the US a production advantage.
2. Natural Resources: The UK was dependent upon many resources from their empire while the US was using a lot of their own domestic resources for production.
3. Decolonialization: the UK’s resource base, as mentioned in the last point, were largely seeking independence in the wake of the war. The US brand of imperialism was more economic in nature than political so they didn’t have the same issue.
4. Population: it’s tough to outproduce a nation that’s 3x the size (UK pop was about 50 million in 1950; the US was roughly 150 million)
5. The Marshall plan. It’s hard to overstate how much of a boon rebuilding Europe was for the American economy.
6. Debt: military goods aren’t cheap. The UK sourced a ton of war material from the US. I just looked it up; the UK made its final WW2 debt payment to the US in 2006. Sheesh!

not the UK who histrionically dominated most of it

I’m sure “histrionically” is a typo, but it still kind of works.

Because there were two world wars that mainly took place in Europe. America was never subjected to bombing or invasion, meaning their industrial capacity was never crippled. They came out on top each time and used their influence and strength to become the new superpower.

This is overly simplified of course.

They massively financially helped and “sustained democracies” that then welcomed USA’s products and culture, growing and becoming world powers themselves (like Italy). The B.E. had a similar chance, but way before, and they just did prey on everything they could (like India or Egypt) until they were kicked out.

The US has a military base in every country, our boot is on the neck of the world.

Don’t worry tho soon the boot will be Xi’s and we will dissappear before we can even think about organizing

my uneducated guess would be guns/military and computers.

because the UK gave up most of that power in the second half of the 20th century, now the UK is a relatively small country (by area and population) that is increasingly isolating itself from the world (Brexit) rather than attempting to influence global politics a lot more than other countries of comparable size, population, and wealth

But the US is slowly losing influence too. In 1990 its side had won the Cold War, but since then other things have happened: 9/11, Iraq War, George W. Bush, the war on terror, Donald Trump; many geopolitical events of the present can be explained (in part) by the fact that the US is losing influence over the world.

As far as I understand it, it’s in terms of soft power. With projects such as USAID (United States Agency for International Development) and others like it, USA maintains the status-quo in it’s favour; however, the new Republican administration have been shooting themselves in the foot by cutting funding for those programs. Thus, the USAs power is diminished.

Likely also a lot of financial things, especially after/during WWII, but I really don’t know enough about that to even guess.

A lot more can be said about the CIAs work in destabilizing “non-American aligned” countries by initiating coups and assassinating/kidnapping democratically elected leaders, but that has arguably done more harm than good to American influence.

*Also it was, for a time, the centre of the world in terms of scientific advancement and urbanism. Los Angeles had what was once the worlds largest tram network that still hasn’t been matched by anyone to this day. Melbourne comes close, but it’s still a fraction of what LAs was… Goddamn shame.

Post WWII the US had massive increases in economic power by exporting a lot of stuff made with our wartime factories as a starting point. The US also is bigger and had a comparable population to Europe, massive amounts of natural resources, and a culture of economic growth and expansion to rival any of the other colonial powers at their peak.

We built on previous empires and went with economics and soft power instead of directly colonizing.

Natural resources, naturally resistant to land wars, capitalism, and trading loans/deficit to fund things that had higher returns than then loan interest.

I am talking out my ass, but didn’t the UK basically overextend itself with its colonies and have to let them loose so it could focus on issues at home?