The federal government allows livestock grazing across an area of publicly owned land more than twice the size of California, making ranching the largest land use in the West. Billions of dollars of taxpayer subsidies support the system, which often harms the environment.

As President Donald Trump’s administration pushes a pro-ranching agenda, ProPublica and High Country News investigated how public lands ranching has evolved. We filed more than 100 public record requests and sued the Bureau of Land Management to pry free documents and data; we interviewed everyone from ranchers to conservationists; and we toured ranching operations in Arizona, Colorado, Montana and Nevada.

The resulting three-part investigation digs into the subsidies baked into ranching, the environmental impacts from livestock and the political clout that protects this status quo. Here are the takeaways from that work.

The system has evolved into a subsidy program for ranchers.

The public lands grazing system was modernized in the 1930s in response to the rampant use of natural resources that led to the Dust Bowl — the massive dust storms triggered by poor agricultural practices, including overgrazing. Today, the system focuses on subsidizing the continued grazing of these lands.