This tweet shows it as a percentage of US GDP:

https://x.com/paulg/status/2045120274551423142

Makes it a little less dramatic. But also shows what a big **'n deal the railroads were!

GDP adjustments are warranted, but it is more stark than both the estimates suggest.

The megaprojects of the previous generations all had decades long depreciation schedules. Many 50-100+ year old railways, bridges, tunnels or dams and other utilities are still in active use with only minimal maintenance

Amortized Y-o-Y the current spends would dwarf everything at the reported depreciation schedule of 6(!) years for the GPUs - the largest line item.

This seems to show the railroads peaking around 9% of GDP. While that's lower than some of the other unsourced numbers I've seen, it's much higher than the numbers I was able to find support for myself at

https://news.ycombinator.com/item?id=44805979

The modern concept of GDP didn't exist back then, so all these numbers are calculated in retrospect with a lot of wiggle room. It feels like there's incentive now to report the highest possible number for the railroads, since that's the only thing that makes the datacenter investment look precedented by comparison.

But doesn't that overstate it in the other direction? Talking about investments in proportion to GDP back when any estimate of GDP probably wasn't a good measure of total economic output?

We're talking about the period before modern finance, before income taxes, back when most labor was agricultural... Did the average person shoulder the cost of railroads more than the average taxpayer today is shouldering the cost of F-35? (That's another line in Paul's post.)

The railroads and the interstate are arguably the biggest and broadest impact, especially in 2nd order effects (everything West of the Mississippi would be vastly different economically without them).

I am not an ai-booster, but I would not be surprised at AI having a similar enabling effect over the long term. My caveat being that I am not sure the massive data center race going on right now will be what makes it happen.

> Makes it a little less dramatic. But also shows what a big *'n deal the railroads were!

It also makes it more dramatic, consider the programs on the list and what they have in common.

* The Apollo program. A government-funded science project. No return on investment required.

* The Manhattan Project. A government-funded military project. No return on investment required.

* The F-35 program. A government funded military project. No return on investment required.

* The ISS. A government funded science project. No return on investment required.

* The Interstate Highway System. A government funded infrastructure project. No return on investment required.

* The Marshall Plan. A government funded foreign policy project. No return on investment required.

The actual return on investment for these projects is in the very long term of decades; Economic development, national security, scientific progress that benefits the entire country if not the entire world.

Consider the Marshall Plan in particular. It's a massive money sink, but it's nature as a government project meant it could run at losses without significant economic risk and could aim for extremely long term benefits. It's been paying dividends until January last year; 77 years.

And that dividend wasn't always obvious; Goodwill from Europe towards the US is what has prevented Europe from taking similar actions as China around the US' Big Tech companies. Many of whom relied extensively on 'Dumping' to push European competitors out of business, a more hostile Europe would've taken much more protectionist measures and ended up much like China, with it's own crop of tech giants.

And then there's the two programs left out. The railroads and AI datacenters. Private enterprise that simply does not have the luxury of sitting on it's ass waiting for benefits to materialize 50 years later.

As many other comments in this thread have already pointed out: When the US & European railroad bubbles failed, massive economic trouble followed.

OpenAI's need for (partial) return on investment is as short as this year or their IPO risks failure. And if they don't, similar massive economic trouble is assured.

I’m surprised there is no broadband rollout or telecom network on there. I guess it’s hard to quantify the cost within a specific event?

The railroad buildout was a lot more, idk, tangible. Most of that money was spent employing millions of people to smelt iron, lay track, build bridges, blow up mountains, etc. It’s a lot more exciting than a few freight loads of overpriced GPUs.

Depreciation schedule:

Tulips: weeks

GPUs: 6 years

Fiber: 20-50 years

Rail, roads, bridges: 50-100+ years

Hyperscalers closer to tulips than other hard infra.

It seems a little silly to put 71 years of private-and-public-sector infrastructure development alongside something highly targeted like the Manhattan Project. It might make more sense to compare the Manhattan Project to the first transcontinental railroad, as a similar targeted but enormously ambitious project amounting to a major technical milestone.

Likewise I don't think it makes sense to compare post-ChatGPT hyperscaler data center construction with all 19th-century US railroad construction. Why not include the already considerable infrastructure of pre-AI AWS/Azure? The relevant economic change isn't "AI," it's having oodles of fast compute available online and a market demanding more of it. OTOH comparing these data centers to the Manhattan Project is wrong in the opposite direction: we should really be comparing a specific headline-grabber like Stargate.

This categorization is just a confusing mishmash. The real conclusion to draw here is that we tend to spend more on long-term and broadly-defined things than we do on specific projects with specific deadlines. Indeed.

As sibling comments mentioned deceptive comparison as well. How about comparing in percentage of Gross Energy Output. https://www.sciencedirect.com/science/article/abs/pii/S09218...