The largest oil refinery in the United States is the Marathon Galveston Bay Refinery, situated in Texas City, Texas. This massive industrial facility boasts a crude oil processing capacity of approximately 631,000 barrels per day. Strategically located near major shipping channels and energy corridors along the Texas Gulf Coast, the refinery plays a pivotal role in supplying refined transportation fuels, petrochemical feedstocks, and heating oils across domestic and international markets. Its extensive configuration integrates complex refining units designed to process diverse crude slates efficiently, making it a cornerstone of American downstream petroleum operations.