This is probably a topic that can only be addressed in AACW2, but maybe a future patch could do something:
The Shenandoah Valley (in western Virginia, running from Harper's Ferry down to Roanoke) was important for two reasons during the Civil War. The first is well-simulated in the game: the valley offers an easy route for invading Confederates to reach western Maryland, but invading Yankees have to cross mountains to get anywhere useful; the valley points away from valuable southern real estate.
The second reason that the valley was important was that it was a crucial source of food for Confederate forces operating in Virginia. In the game, the three cities in the valley, Covington, Winchester, and Harper's Ferry, produce a total of 58 general supply at the beginning of the 1861 scenario. This while Richmond produces 154. It is true that GS is a larger category than just food, and Richmond produced a wide variety of products useful for an army.
At the beginning of the 1863 scenario, the various Confederate forces in the Virginia theater consume 390 GS a turn. They control Winchester at the start of the scenario, but it is not garrisoned.
The CSA player can pretty cheerfully give up the Shenandoah Valley without suffering any serious supply problems in Virginia. I'd like to see some of the GS production currently assigned to Richmond, Petersburg, Charlottesville, and other Piedmont cities transferred out to the Valley, maybe with the addition of a couple more towns between Covington and Winchester. I suggest Staunton and Front Royal as being considerable market towns in the period that were fought over. You could also add Harrisonburg and Roanoke. If these were all level 1 towns with a couple dozen GS production each, this would make both sides pay a little more attention to this region than most players seem to now. Maybe there will even be a Jackson's Valley Campaign!