Northern blockade will create a food shortage
Problems that will lead to the shortage
During this civil war many men have joined the, leading to their being less people to pick food, also many slaves have ran away compounding this problem. Inflation also led to money being able to buy less food. Finally the north blockaded the south with their navy leading to us being unable to bring in supplies by trade.
Effects of this shortage
The food shortage led to riots in 1863 with people robbing bakeries and other food shops. Though this caused the south to dispense some of its rice stocks, you should not do this as it as the civilians should be willing to take on hardships like the soldiers and not riot which will actually hurt the economey.