He misses one thing with it comes to resources.
Yeah the "country" produces much of the food, energy etc. But All of the material they, (fertilizer raw material) use comes through Ports in large Cities.
There are literally HUNDREDS of major ports in the US, if not more than that depending on how you define 'major'. There are hundreds more that have the equipment to load and unload vessels, with the only limiting factor being the size of the boat.
Infrastructure wise and transportation wise, big international shippers have gone to using massive vessels with deep drafts, which require deep water ports with certain criteria for loading, unloading, and for maneuvering a boat that is over 1,000 to 1,300 feet in length.
What can happen though is those larger boats can park offshore and smaller boats can ferry items pretty much anywhere. In the oil business this process is called 'Lightering'. It's where a smaller boat pulls up to a much larger boat and ferrys the cargo bit by bit to shore.
In other industries they have vessels that can offload anywhere at sea if they want, which would essentially be the same thing.
Back in the day they were (and still are) transporting goods up and down the Mississippi river (as an example). Most of the smaller ports in the US are for regional trade...for example sending something from Louisiana to South Carolina, and more importantly though the vessel size and design allow for this. Those smaller boats though in a whole lot of cases are more than capable range wise of carrying cargo on trans Atlantic voyages if needed. As a primary example 99.99% of the oil we now export to Europe is carried on small tankers that have more access to vast numbers of ports that the bigger tankers can't get to.
Hauling things from China to LA is a whole different animal, but then again those things were created to maximize 'efficiency' or so they say.
Edit: Another fun fact regarding the oil industry in the US. The US has almost NO ports that can accept a VLCC tanker (some of the largest ones). The oil companies would either lighter the oil to shore on smaller vessels via ship to ship transfer, or they would unload in deep water ports on a variety of Caribbean islands to storage facilities there.
When we wanted said oil we could just use a smaller boat and go get it when needed.
In any case when there is a problem there is definitely a solution. In other words if we want to get stuff here, we can get stuff here.