Pipeline safety regulators have imposed their largest fine ever on the company responsible for leaking 1.1 million gallons of oil into the Gulf of Mexico off the Louisiana coast in 2023.

The nearly 2,700-mile Keystone oil pipeline was shut down Tuesday morning after it ruptured in North Dakota, halting the flow of millions of gallons of crude oil from Canada to refineries in the U.S. and potentially leading to higher gasoline prices.