What would cause the trucking industry to stop interstate transport? A war between Israel and Iran would do the trick nicely, causing Iran to scuttle ships in the Strait of Hormuz like they've repeatedly threatened to. That would stop a large percentage of oil from being delivered to market, driving up gasoline prices to unaffordable levels. Besides the direct effect that has on trucking, it will also have a strong effect on social unrest by further aggravating the economic collapse and unemployment at the same time that police departments have to cut back, making our roads the haunts of robbers and highwaymen.

People dying from lack of salt? Yes. America has much more water and food than salt. A person can survive many weeks with no food, but less than one week without salt.

Why do you suppose the first international highways in history started out as salt traders' caravans? Or why the Romans paid there soldiers in salt instead of gold or silver? because those ancients were acutely aware of something our modern age has forgotten : our vulnerability to salt deprivation.

Lack of clean water is a solvable problem, simply by filtering and boiling water. But the only way to get salt is to buy it from someone else, unless you live on top of a salt mine or are on the coast and can procure it from evaporating seawater.