It's hard to imagine, but if it weren't for Clarence Birdseye, frosted foods might not be the popular digestible comestible it is today. The pioneering Birdseye sought to improve the sorry state of frozen foods at the turn of the last century by replicating the almost immediate effect Arctic climate had on caribou meat, a technique that he had witnessed on an earlier expedition. His preliminary freezing experiments at his home in Brooklyn were overwhelmingly successful, and he transformed his new method into a successful fish-freezing business in Gloucester, Massachusetts in 1924. It was at this time that he developed the characteristic rectangular block o' frozen food, using a machine that simultaneously shaped and flash-froze anything fed into it.
Once Birdseye had perfected his freezing technique, he had yet another obstacle to face: the public. Carolyn Wyman recounts in her brilliant book, Better Than Homemade, 'Consumers had no reason to think his frozen food would be any better than the old kind...[And,] perhaps most critically, Birdseye had overlooked an essential fact: Few grocers and even fewer consumers owned freezers.' But, after receiving backing from the Postum company, Birds Eye brand gradually began to saturate markets in the early 1930s, and, to further boost their sales, their frozen products were sold to schools and hospitals. It wasn't until World War II, when time and resources were limited, that the concept of frozen foods, and Birds Eye in particular, burst into popularity. This advertisement is from 1945. It highlights one of the major selling points of frosted foods: vegetable availability year-round, regardless of seasonality.
Note, also, the advertisement for Birds Eye Open House starring Dinah Shore.
Once again, I highly recommending reading Carolyn Wyman's Better Than Homemade: Amazing Foods That Changed The Way We Eat.