In April 2020, it was lack of storage capacity at Cushing which turned WTI petroleum futures contracts negative for the first time in history. While Cushing has maximum storage of about 90 million barrels across 15 terminals, working storage is more like 76 million barrels, about 13% of total U.S. oil storage capacity. With 59.5 million barrels stored, little demand for oil from customers, and much of the remainder of the storage capacity already booked, traders holding contracts for hundreds of thousands of barrels of oil for delivery at Cushing on April 21 realized they had no place to put the oil, and storage fees charged under the contracts for not taking the oil could be astronomical. Thus paying a party having already-contracted storage capacity to take the oil was cheaper than incurring those contractual storage fees.