Throughout World War I in the United States, dairy farmers struggled. Feed prices went up, and retail prices of milk went up, but the wholesale prices that farmers got from milk dealers and dairies remained static. Despite dozens of local and state and federal inquiries, no single culprit for high milk prices was ever discovered. The result of high prices combined with government advocating for increased production and Progressive Era ideas about the importance of cow's milk in the diet, particularly for children, meant that by the spring of 1918 there was a serious milk surplus. For several years, the butter, cheese, and condensed milk industries had absorbed the milk surplus, but by the spring of 1918 they were also over capacity.
The United States Food Administration, in conjunction with state governments, embarked on a campaign to try to get Americans to consume more milk, with limited success. In May of 1918, New York City hosted the National Milk and Dairy Farm Exposition at the Grand Central Palace. New York State Governor Charles Whitman opened the exposition, and United States Food Administrator Herbert Hoover also attended. Home economists praised milk-based dishes such as puddings, custards, and the use of cottage cheese and brick cheeses - hence the phrase "Eat more milk," rather than "drink," as drinking cows milk was not common among adults. Cottage cheese and brick cheese were touted as affordable meat alternatives. Despite the classic Progressive Era boosterism, including the attendance of "famous" cows at the exposition, retail milk prices remained relatively high, with seasonal dips in the spring and early summer.
Federally fixed milk prices helped solve the problem short-term, but even after the war, dairy farmers were subject to a Congressional investigation to determine whether they price gouged consumers (they didn't), and the right of farmers to form co-ops was in danger of becoming illegal under anti-trust laws. Ultimately, it was falling grain prices and rising postwar demand that evened out prices, although to this day the dairy industry still struggles.
Even after the war, Progressive Era ideas about the importance of cow's milk in the diet persisted, and were recycled during the Second World War.