Information on factory farms is spotty at best. The government has been hogtied from doing more.

CAFOs have been a point of contention between the livestock industry and environmental activists since they began to proliferate in the 1990s, overtaking small, pasture-feeding operations as the dominant form of animal agriculture in the US. As the number of livestock producers has declined, the number of animals — hogs, cattle and poultry — has skyrocketed over the past several decades, in part due to rapid consolidation in the industry.