Drew has linked to maps by the NYT on the impact of oil prices by county. The county that spends the highest fraction of its income on gas is Wilcox County, Alabama. Wikipedia has the census data on Wilcox County: 13 thousand people on 2500 square kilometres. The County seat is a town of 2250 and maybe one other town in the county has more than 500 people. Google maps satellite pictures show a mosaic of shades of green and ochre indicating it's divided up into farms. I'm guessing maybe up to 1/2 of the population of the county lives in the towns and he rest live on farms, with houses a kilometre away from each other in some areas?