|Dairy cows at Appleton Farms in eastern Massachusetts|
Take dairy. It's one of the agricultural sectors most overlaid with both nostalgia (think milkmaids, butter churns, black and white Holsteins on a Vermont hillside) and ideology (think childhood nutrition, school lunch subsidy, and the raw vs. pasteurized debate). It's also one of the liveliest frontiers of local-food revitalization (think urban professionals turned artisanal cheesemakers).
Yet it's a component of the food system whose history is particularly murky and ill-understood.