This is the United States of Planned Economies!
Introduction
The question posed by this thread is whether the United States can outproduce the world. In order to undertake this experiment, I took control of the USA and followed a few simple rules.
1) No CGM
2) Capital ships in the build queue will be finished before the war starts (but not necessarily right away).
3) I will not raise threat on anyone to get laws early.
4) I will not game factions to join the war early.
5) I will trade with the world via autotrade (no starving the Axis).
6) I will not occupy IC or resources (turned out to be moot; see below).
7) I will buy or sell supplies as needed (turned out to be moot; see below).
8) No manipulation of dissent to change politics or engage the "Prepare for War" decision.
This is a production test, so the US will only defend its shores. It will not fight at all except to protect convoys (turned out to be moot; see below) or defend its currently held bases. Per other production tests I've done, occupying enemy territory and resources, even a little, can throw off results.
Also, since we are not trying to test whether or not the US can reach specific military production targets, I will just build IC, supplies, or anything else I deem necessary.
Short version:
I achieved this level of production before resources were exhausted:
Moot Points:
Before going any further, we need to talk about what IC investment to the tune of 1505 effective IC does to the game. First, it turns the US into a net importer of raw materials. This severely hurts the Allies, as it cuts them off from their usual supply of rares, energy, and steel. Britain found itself losing to the Axis in the Med and India even before Japan declared war.
But even more important, if the US is a net importer, Japan won't declare war because the US ends up importing resources from even Japan and Germany. In this game, thanks to the insatiable desire of US IC for resources, the US is desperately trading with everyone it can. And since US flagged convoys are moving German and Japanese coal to US shores, the blockade against the Axis powers is only halfway ineffective. Hitler's war ends up being partially financed by US dollars.
The result of this is that I had to manually declare war on Japan using the noneutrality cheat on January 2nd, 1942, just to see what US IC looks like under maximum laws. I didn't even have enough threat to DOW without noneutrality thanks to how the war was turning out.
Building IC
Aside from the initial ships in the queue at game start, I purely built IC the entire time. It is a very boring way to play. That being said, it takes a long time to get construction practicals up. Normally, I might cook some other stuff that I need to get initial practicals in place, but since IC is the only thing I care about, that's all I built. I eventually reached a 71% cost and time reduction in construction practicals, but most of that reduction didn't kick in until 39.
The reason is because the New Deal sucks out a ton of IC into consumer goods. I used a consumer goods reducing minister until 39 to cut this cost, and then switched to a resource minister and started monitoring my trades heavily (keeping resources up). The US does not have an IC minister you can appoint under FDR's government, and I wasn't going to manipulate my politics using dissent. (There is a spare IC minister somewhere; a vice president I think.)
The lack of threat throughout this particular game (and I'm not raising it myself) makes it harder to get better production in place even after the New Deal is removed. A lot of US IC is tied up in bad laws; but once the floodgates open in late 1939, you can produce tons of IC.
One further problem with US laws is consumer goods orientation; while it has advantages, once you get past 600 IC or so, the boost you could hypothetically get from heavy industry emphasis outweighs the extra consumer goods. But since I can't turn communist, it's a moot point.
Resources
As you can see in the above picture, the US is 24 hours away from a national crisis of coal. While there is plenty of coal (and in HOI3, energy more or less means coal, since you can't trade hydroelectricity or nuclear power to other countries that are across oceans in 1936), most of the world's coal is either tied up in the war or consumed by other countries. I reached 1505 IC, but it is not sustainable.
But resource numbers in January of 1942 only tell part of the story. It turns out that sucking all the world's resources towards the United States screws, well, everyone. Part of the problem is that the US ends up importing everything. Rares are the first thing she needs to import, but good relations with the Soviets and Britain can help cover some of that. But eventually, coal takes the lead. And the US sucks up all the free coal in the world, even from the Axis, as time goes on.
But that means a ton of smaller minors are more or less starved for energy. And eventually, even majors like Britain start to feel the hurt as they mobilize their economies.
The problem is acute. When I totaled up the IC of various powers, I thought some countries seemed to be a bit low (Australia, New Zealand). It turned out that several Dominions and other minors had low IC because they couldn't fuel anything. The world of HOI3 really depends on trade (good), but when the US just buys every damn thing and never exports a single unit of raw materials, the system crashes. Canada and Hungary and Romania were fine, but some minors had less effective IC than base IC even at full economic mobilization.
This actually helped me achieve my goal, as it lowered the IC bar a tad.
World IC
Calculating world IC was kind of a pain in the arse (I'm not doing it again, either). Part of the difficulty, aside from tag switching to every damn country, is that it's always in a bit of flux. Between occupations, resource starvation, and ministers, in a month it can swing back and forth considerably.
By my count, the world had a total of 1476 IC. But this figure is derived from Japan occupying most of India, a stalemate in Barbarossa that stopped well short of Leningrad, a UK that is starving for resources (both lost convoys and lack of resources), and a Soviet Union that has just had its special decisions expire. Some specific numbers:
GER 350
SOV 288
ITA 123
Japan 207
ENG 150
Sweden 35
Canada 56
Romania 57
Hungary 47
Switzerland 21
I would like to point out another little detail. The Soviet Union had a hard time enacting better laws this time when the war started. Barbarossa started significantly later than usual for some damn reason, and even after it started, the Soviets didn't have enough money to get their laws into gear when it started. I'm not entirely sure why the Soviets had so little money even after the shooting started, but someone might argue that economic problems nerfed Soviet IC to lower levels than it should be. But in reviewing other save games, SOV IC seems roughly on par with what it should be.
I do wonder what the weird threat levels have done to the IC of other countries, though.
Conclusion
The game's economy is not really designed to handle the kind of economies of scale that come into play under these circumstances. We've seen how the game's edges fray when I've run other production tests, but I think this test shows just how interdependent the world economy is in HOI3.
Given resource limitations, a more reasonable sustainable amount of IC would probably be around 1000 effective IC, depending on how effectively you can stockpile rares and energy. (After the energy crash on January 4th, the effective IC of the USA in the above game is 992, with a continued deficit of 136 rares per day even at the level.)
I do think that, despite the relatively short-lived nature of the IC production peak, that this test demonstrates that in HOI3, the USA can outproduce the entire rest of the world for a very brief amount of time. To say that the USA in HOI3 can outproduce the rest of the world is not an insane statement to make, even if the strategy that leads you to a point where the US can outproduce the world is not optimum for winning the game.