PHOTO: LIBRARY OF CONGRESS

Held in Milwaukee in 1924, the National Dairy Show demonstrated the titular industry's progress in safety to a wary public. With a massive typhoid outbreak that occurred in New York just 11 years before blamed on contaminated milk, the industry took pains to stress to the 223,000 attendees, for example, the recent mandatory pasteurization of the beverage. For this United States Department of Agriculture exhibit, the government agency emphasized how adding lime to the soil increases calcium or magnesium in the grass that is ultimately fed to cows, which in turn produce more and healthier milk.