Can food shortage happen in America?
This sounds like an absurd question. With so much arable land, it would never happen in the US.
The truth is, it may very well happen in America.
In real life, shortage may not always happen due to greater demand.
The fundamental for agriculture products are very sound. There is worldwide population growth while arable land has not been grow in sync. By Mathusian theory, there are three effective way to control the population: War, Decease and Hunger. We have not had the large scale war and decease in last 50 years. The world population has ever grown. Both cause the demand increases worldwide.
But what will cause the food shortage in the US?
The clear culprit is the unstable currency. Just ask yourself, would you sell any thing that you may sell more tomorrow (if the goods will not rot)?
In that case, people store their food and every thing storable. They will wipe out the merchandises in the store to cause shortage. Therefore, the food shortage will then born.
Be prepared.
