The latest leak in the Keystone oil pipeline in North Dakota on Tuesday continues the troubled history of the 15-year-old pipeline. The 2,700-mile-long (4,350-kilometer-long) pipeline originates in Alberta,

The Keystone oil pipeline from Canada to the United States was shut on Tuesday after an oil spill near Fort Ransom, North Dakota, its operator South Bow and the state's Department of Environmental Quality said.

The cause of the rupture and the total volume of oil released after the North Dakota spill remain unclear, officials said.