Advances in refrigeration and the development of a nation-wide transportation system made the egg a shippable commodity. The modern incubator made it possible to industrialize chicken and egg production. In the 1930’s, commercial breeders, land-grant universities, and the USDA worked to develop ever-more productive strains of egg-layers, and new equipment and techniques for production.

The result, ultimately, was that backyard and small-farm egg flocks were replaced by a highly specialized, consolidated industry.

The size of modern egg “farms” is staggering. According to the United Egg Producers, there are currently 62 egg producing companies with flocks larger than one million layers, and 12 companies with flocks of more than 5 million. In all, there are approximately 200 egg producing companies with flocks of 75,000 hens or more. These companies represent about 95% of all the layers in the United States.