Keystone Mapping Project: Oil Spill Voluntary Evacuation Zone. Border Montana, North Dakota, and South Dakota. Published July 5, 2012 at 1000 × 592 in Keystone Mapping Project: Oil Spill Voluntary Evacuation Zone. Border Montana, North Dakota, and South Dakota. Two-mile Voluntary Evacuation Zone.; Proposed Keystone XL route.; Border Montana, North Dakota, and South Dakota.