It's not getting much attention, but American dairy farmers are in trouble. Back in the old days, when farmers were a third of the American workforce, such a thing would be a first-rank political issue. But now, when they're about 1 percent, it's easy to ignore. (To be fair, President Trump is sort of paying attention, even if he is blaming the wrong people.) Nevertheless, it is still a problem worth fixing, both because farmers are still a significant presence in many states (not to mention our, you know, fellow citizens), and because the dairy problem illustrates how government policy can help stabilize and rationalize the production of vital commodities. The proximate problem is about exports, as a new Canadian price regulation (not a tariff, importantly) to protect their own dairy farmers has made it impractical to export ultra-filtered milk there.