oilsupplyU.S. crude oil inventories at the end of February held the most days of supply since the mid-1980s, according to the U.S. Energy Information Administration.

Inventories could supply 29 days of refinery demand in the United States.

“The number of days of supply is calculated by dividing the commercial crude oil inventory level at the end of the month by the forecast crude oil refinery runs in the following month,” according to EIA. The U.S. Strategic Petroleum Reserve is not included in the calculation.

Inventories are high across all the 34 countries in the Organization for Economic Cooperation and Development, of which the United States is a member.