While planning for the defense of the Hawaiian islands in the wake of the attack on Pearl Harbor, the U. S. Army hastily built an access road in 1943 across the Humuula plateau of Parker Ranch at . Since it was not intended as a civilian road, the simple gravel path was built by the Civilian Conservation Corps and the US Army Corps of Engineers in case of an invasion. Military vehicles of all types and treads traversed the Island for the next three years.