And supply chains! There are many things that a 1918 city could manufacture in an emergency that a 2020 city can't.
Today, no sawmills, no regional tool and supply manufacturers, no regional raw materials. Iron ore from the lake Champlain area could be smelted in the Albany area and made into nails in many places.
Today, you’re 100% dependent on diesel and open roads to Newark, the I-81 corridor and rail traffic from the west for food. 75% of the regional produce producers of gone. Most (50-70%) of whatever is left of dairy production will be driven into bankruptcy this year.
I'm not sure if it is needed though: there is probably more than enough lumber in the local lumber yards currently intended for local construction projects but when nobody is building/remodeling...
Actually I live in a manufacturing city so I'd expect we would be making ventilator parts, since I don't have machining experience I'd be repurposed to packing the parts into boxes. Any city has enough tablesaws to build beds, not every city has as many people who know how to run a lathe as mine.
The short term consumables or raw resources are the ones that matter the most. If people stop going to work to make bread or toilet paper or refine oil it's going to put a strain on a lot of things. The oil and chemical industries are really going to be important for producing medical items like gloves, sanitizer, cleaning agents, plastic ventilators, sanitary plastic containers for equipment and needles, etc. Not to mention the effects of lower oil production and the strain and cost on shipping those things back and forth to their respective factories.
But it will have to be pretty bad before we have to worry about that I think.
One of the reasons why panic, and the resulting changes in consumer demand for certain products, is so dangerous. Not because stores are running out of toilet paper, but because of the mid term effects this has on availability of all kinds of things. This effect is impossible to predict upfront.
So, yet another reason to stay calm and avoid this kind of stress on supply chains providing goods of daily need.
All other steps involve buffer stocks and inventories. This inventory is sitting local warehouses for example. Or just dead weight in the various locations. More often than not, this is due to inefficiencies.
That beingsaid, JIT is simply to hard to implement to use it for anything else then the most important parts. and even there only for the very last step, everything else smply has to many variables for JIT to work.
The best example are automotive supply chains that kept running all the time through February.
And stuff like groceries are not run JIT, with the exception of the replenishment of shelves and local stores from a regional warehouse. And that is not true JIT.
These critical porducts, and the coresponding manufacturing base, will be part of the critical infrastructure to be kept running. Automation is a huge benefit for this, as these operations can be run with a very limited number of people. Distribution and transportation is the same, it can be kept up for the essentials with a very limited amount of people. Even internationally, container ships continued to sail from Chinese ports. Granted, sometimes they sailed empty, but that was due to the shut-down of Chinese manufacturing.
In a true worst case scenario, dedicated ports will be kept running. again wth close to no people involved.
Administration for all this can be done to a huge part from home. Feet on the ground are by no means as important anyore as they used to be.
a situation like this should be avoided at all cost so. Hence the measures currently being taken.
Picture of some hospital beds from around that time: https://images.theconversation.com/files/225680/original/fil...
The hard part is the basics - things that get commoditised tend to get manufactured more efficiently, and at massive scale this tends towards centralisation.
As a concrete example, in the entire country of New Zealand, no one manufactures window glass. Every window, everywhere in every building, ultimately gets shipped into that country in a container.
We'd also miss shoes as there are no "real" factories locally anymore. I think we make nails but I can't tell if we can really make bolts. So I'm not talking about cars, computers or aircraft. No way. Windows. Shoes. Bolts.
So OK, we're missing commodities, most industrial chemical processes, feedstocks, experienced manufacturing labour and plant expertise, all of which went south when NZ was one of the first countries to drop its pants and remove import tariffs. OK. I don't have a dog in that fight, there are reasonable arguments to stop subsidising things you'll never be internationally competitive at.
That said if all imports stopped tomorrow for, let's say, 2 years, it's surprising what you can do without or improvise. The main thing I think we'd really miss is life sustaining medicine. A loss of exports would actually be more catastrophic since our farmers would a) have no reason to exist and b) not be able to keep the finance wheels turning.
We're unbelievably wealthy compared to people in 1918 and we have a lot more slack and fat in our systems than we really know.
Yes, we need flexible chemistry machines on the style of CNC mills. The good news is that they aren't that far away, at the next pandemics we will probably have them.
It's probably going to be more difficult to find something that is still widely used and is manufactured, but cannot be manufactured in a particular city in 1918 but not 2020. It would require deep knowledge of the industries of a particular city or of a particular industry. For example, right now I think all three of the ruling engines in the US capable of cutting a research-grade diffraction grating into glass are in the single Richardson Gratings lab in Rochester, New York, but one of them was built at MIT before 1918. So perhaps Boston (or Cambridge at any rate) was capable of producing such artifacts in 1918, but not today; but, if that is true, rigorously establishing the truth of that claim would require considerable investigation.
Similarly, many US cities have many fewer watchmakers, compounding pharmacists, and piano tuners than they had in 1918; in some cases the number is indeed zero.
Realistically, where would you start with these in a typical deindustrialized town today? "A factory" is a poor answer, some towns have none really, and factories are not interchangeable anyway.
If your plan for resilience against a long-term disruption of global trade has a critical dependency on global trade, you may need to rethink it somewhat.