As of September 1 (the latest data available), the United States had 18.4 million barrels per calendar day (b/cd) of petroleum refining capacity, also known as operable atmospheric crude oil distillation capacity. U.S. refining capacity had reached a record high of nearly 19.0 million b/cd earlier this year, but several refineries have closed since then and reduced capacity to the lowest level since May 2016.