Roughly 4 million acres of land and several million square miles of ocean. That's how much territory Obama protected during his presidency. At the center of his efforts is a Roosevelt-era law called the Antiquities Act which allows presidents to designate "objects of historic or scientific interest" as National Monuments.

In September, the Trump administration recommended changes for 10 of these monuments. These alterations include either shrinking their size or opening them up to "traditional uses" like mining, timber farming, drilling, and commercial fishing.