The largest oil refineries in the US are led by Motiva’s refinery in Port Arthur, Texas, which can process about 656,400 barrels of crude oil per calendar day, according to the U.S. Energy Information Administration’s (EIA) Refinery Capacity Report. Barrels per calendar day is the operator’s estimate of how much crude its distillation units can process in 24 hours under usual conditions, after allowing for scheduled and unscheduled maintenance. Eight of the ten largest refineries sit in Texas or Louisiana, based on the EIA’s figures as of January 1, 2026. Together, these ten plants can process about 5.3 million barrels per calendar day, roughly 29% of the 18.2 million barrels the EIA counts across 130 operable refineries nationwide. If you were hurt at a refinery, The Buzbee Law Firm offers free consultations at 800-992-5393.
The order can shift as plants report new capacity or close. Port Arthur regained the top spot in the 2025 report after reporting higher throughput, and the 2026 report reflects two refineries that stopped refining in 2025, which together removed about 400,000 barrels per day of U.S. capacity.
1. Motiva Port Arthur Refinery, Port Arthur, Texas
Motiva Enterprises, owned by Saudi Aramco, runs the largest refinery in the country at 656,400 barrels per calendar day. A 2012 upgrade first put it at the top of the national rankings.
2. Marathon Galveston Bay Refinery, Texas City, Texas
Marathon Petroleum’s Galveston Bay refinery processes 631,000 barrels per calendar day, and it held first place in the EIA’s 2024 rankings. Measured in barrels per stream day, which assumes the plant runs at full capacity with no downtime, it is the largest in the country at 678,000 barrels. Stream day figures typically run about 6% higher than calendar day figures.
The plant was formerly BP’s Texas City refinery, where a 2005 explosion killed 15 workers and injured 180 before BP sold the plant to Marathon in 2013.
Federal law addresses that kind of risk through the Occupational Safety and Health Administration (OSHA) and its process safety management standard, which sets requirements for preventing or minimizing catastrophic releases of toxic, reactive, flammable, or explosive chemicals. It covers processes holding 10,000 pounds or more of a Category 1 flammable gas, the most flammable class under OSHA’s hazard rules, or of a flammable liquid with a flashpoint below 100°F (37.8°C), at one location, subject to listed exclusions, so coverage is decided process by process. Whether a plant met those requirements can become a central question after a fire or chemical release injures workers.
3. Marathon Garyville Refinery, Garyville, Louisiana
Marathon’s Garyville refinery processes 617,000 barrels per calendar day, more than three times the 200,000 barrels it could handle when it began operating in 1977. It gives Marathon two of the three largest refineries in the country.
4. ExxonMobil Beaumont Refinery, Beaumont, Texas
ExxonMobil’s Beaumont refinery processes 612,000 barrels per calendar day, and a 2023 upgrade moved it into fourth place nationally. With Motiva’s plant and Valero’s Port Arthur refinery at number nine, the Beaumont and Port Arthur area is home to three of the ten largest refineries in the country.
5. ExxonMobil Baytown Refinery, Baytown, Texas
ExxonMobil’s Baytown refinery processes 564,500 barrels per calendar day and is one of two Houston-area plants on this list, along with Galveston Bay. One of the 2025 closures was also nearby, where LyondellBasell ended refining operations at its Houston plant.
6. ExxonMobil Baton Rouge Refinery, Baton Rouge, Louisiana
ExxonMobil’s Baton Rouge refinery processes 523,500 barrels per calendar day. With Beaumont and Baytown, it gives ExxonMobil three refineries in the top ten and about 1.7 million barrels per calendar day of combined capacity, the most of any company on this list.
7. Citgo Lake Charles Refinery, Lake Charles, Louisiana
Citgo Petroleum’s Lake Charles refinery processes 471,200 barrels per calendar day. It is the third Louisiana refinery in the top ten, along with Garyville and Baton Rouge.
8. BP Whiting Refinery, Whiting, Indiana
BP’s Whiting refinery processes 435,000 barrels per calendar day and is the only refinery in the top ten located in the Midwest, which also makes it the region’s largest.
9. Valero Port Arthur Refinery, Port Arthur, Texas
Valero’s Port Arthur refinery, operated through its Premcor Refining Group subsidiary, processes 385,000 barrels per calendar day. It is Valero’s only plant in the top ten, even though Valero is one of the three largest U.S. refiners by total capacity.
10. Marathon Los Angeles Refinery, Carson, California
Marathon’s Los Angeles refinery in Carson processes 365,000 barrels per calendar day and is the largest refinery in California, with nearly a quarter of the state’s crude oil refining capacity, according to the California Energy Commission. The commission notes that Marathon’s Carson and Wilmington plants began reporting as one refinery in 2019. The combined plant is the only West Coast refinery in the top ten.
Hurt at One of the Largest Oil Refineries in the US?
A fire, explosion, or chemical release at a plant this size can upend a worker’s life and a family’s finances in seconds. The Buzbee Law Firm represents people hurt in refinery accidents, including those who suffer burn injuries, and our past results include a $280 million settlement for multiple plaintiffs after a plant explosion. A refinery injury claim can involve parties beyond the employer, such as contractors or equipment manufacturers. For an injury at a Texas refinery, a personal injury lawsuit generally must be filed within two years, so contact us or call 800-992-5393 today for a free consultation about an injury at one of the largest oil refineries in the US.