CANNON BALL, ND - NOVEMBER 30:  Police stand guard to keep activists of a bridge near Oceti Sakowin Camp on the edge of the Standing Rock Sioux Reservation on November 30, 2016 outside Cannon Ball, North Dakota. Native Americans and activists from around the country have been gathering at the camp for several months trying to halt the construction of the  Dakota Access Pipeline. The proposed 1,172 mile long pipeline would transport oil from the North Dakota Bakken region through South Dakota, Iowa and into Illinois.  (Photo by Scott Olson/Getty Images)