CANNON BALL, N.D. – Authorities on Thursday cleared a protest camp where opponents of the Dakota Access oil pipeline had gathered for the better part of a year, searching tents and huts and arresting three dozen holdouts who had defied a government order to leave. It took 3½ hours for about 220 officers and 18 National Guardsmen to methodically search the protesters’ temporary homes and arrest people, including a man who climbed atop a building and stayed there for more than an hour before surrendering. Native Americans who oppose the $3.8 billion pipeline established the Oceti Sakowin camp last April on federal land near the Standing Rock Indian Reservation to draw attention to their concerns that the project will hurt the environment and sacred sites – claims Dallas-based pipeline developer Energy Transfer Partners disputes.