CIWF defines "megafarms" based on USDA Census of Agriculture data, focusing on the largest farms. Definitions by species are provided below.

Dairy Megafarms

Dairy megafarms, with over 500 cows, are heavily concentrated in central California, with smaller hotspots in northern Wisconsin, southern Idaho, and the Northeast. California is the nation’s leading state in dairy production, and this puts another strain on California’s already depleted water resources. Large-scale dairy farms significantly reduce cow welfare and increase environmental pollution, because methane emissions from these farms contribute to global warming.

Beef Megafarms

Beef megafarms, housing over 500 cows, are the most widespread, covering the entire western United States. Cherry County, Nebraska, has more beef cattle than people. These farms, like dairy farms, produce a lot of methane due to the cows' size and increased need for food and space. To maximize profits, companies crowd cows into small spaces, creating poor living conditions for the animals and a massive environmental footprint.

Hog Megafarms

Hog megafarms, with over 1,000 hogs, are concentrated in northern Iowa and southeastern North Carolina. Hogs produce up to ten times more sewage than humans, stored in open-air lagoons that release methane and can overflow, contaminating water with excess nitrogen and raw sewage. High nitrogen pollution areas often overlap with hog farm locations, indicating their role in environmental degradation, as seen in the gif under "Environmental Implications and Effect on Animals." These farms are typically built in low-income areas where residents often lack the resources to fight back.

Laying Hen Megafarms

Laying hen megafarms, housing over 20,000 chickens, are less common but still detrimental to animal welfare. Hotspots for laying hens are in Pennsylvania, North Carolina, Alabama, and Arkansas. Some of these farms house millions of chickens, leading to severe crowding, shortened lifespans, and sensory deprivation. While some farms have adopted cage-free practices, many have not.

Broiler Chicken Megafarms

Broiler chicken megafarms, selling over 500,000 chickens annually, are primarily found in the southeastern United States, with hotspots in Arkansas, Alabama, Mississippi, and Delaware. These farms face similar issues as laying hen farms, with overcrowded conditions that reduce animal welfare and food quality. The USDA tracks chickens sold rather than inventory, as broilers are often slaughtered at six weeks, making inventory hard to track.

Environmental Implications and Effect on Animals

Megafarms are a significant strain on the environment. Animals need a lot of space, food, water, and enrichment to produce quality goods for humans to consume. However, megafarms are so large that it is difficult to effectively give each animal the care they deserve. Matters get worse when the megafarm is a CAFO, with animals all packed together, because this leads to the spread of disease, no room for the animal to spread out, deprivation of the senses, elevated stress levels, and much more.

In addition to the welfare problems that arise when animals are raised in CAFOs, these farms are detrimental to the environment. Cow megafarms are particularly bad for the environment, since they are large and resource intensive animals. Cows emit methane, a highly potent greenhouse gas that warms the atmosphere twenty-eight times as much as carbon, as a byproduct of their digestive systems. Hog farms are also dangerous to the environment, but for a different reason.

Hogs produce ten times as much waste as humans do, but their waste is not treated in the same way. Their waste is stored in lagoons, which are open-air pits where the waste sits on the farm. If the lagoon overflows, that waste ends up in the waterways. Nitrogen from the hog waste causes biodiversity die-outs in lakes and rivers, which lead to environmental complications as the systems are thrown out of balance. There is a strong correlation between hog farm density and the areas of highest levels of nitrogen pollution, as seen in the gif below. The red spots represent concentration of hog farms, while the areas of dark blue are the watersheds with the highest levels of nitrogen in the water.