Marathon Petroleum refining is the second-largest petroleum refining operation in the United States by throughput capacity, processing approximately 3 million barrels of crude oil and feedstocks per day across 13 refineries concentrated on the Gulf Coast, in the Midwest, and on the West Coast. Headquartered in Findlay, Ohio, and trading on the NYSE under the ticker MPC, Marathon Petroleum generated revenue exceeding $150 billion in 2023 and operates the most integrated refiner-midstream structure in North America through its sponsorship and control of MPLX LP — a $45 billion market capitalisation midstream MLP that handles crude supply, product distribution, and natural gas gathering and processing across the refinery network and beyond.
Marathon Petroleum Refining: Refinery Network and Configuration
Marathon Petroleum’s 13-refinery network spans three primary operating regions. Gulf Coast refineries — including the Garyville, Louisiana facility at approximately 578,000 bpd, one of the largest single refineries in the United States — anchor the system with deep-water crude access and direct connectivity to Gulf Coast export infrastructure. The Galveston Bay refinery in Texas City, with capacity exceeding 450,000 bpd, is the second-largest facility in the network and among the most complex refineries in the US by Nelson Complexity Index rating.
Midwest refineries serve the interior US product market from locations in Illinois, Ohio, Kentucky, Michigan, and North Dakota. The Robinson, Illinois refinery is the operational hub of the Midwest system, processing primarily light sweet crude from Permian and Bakken pipeline deliveries. Midwest refinery positioning gives Marathon access to advantaged inland crude differentials when pipeline-constrained Canadian and Bakken barrels trade at discounts to Gulf Coast waterborne benchmarks — a structural earnings advantage that Gulf Coast-only refiners cannot capture.
West Coast operations were significantly restructured following the 2020 sale of the Speedway retail network to 7-Eleven for $21 billion. The Martinez, California facility — converted to renewable fuels production as the Martinez Renewable Fuels plant — represents Marathon’s primary West Coast asset in 2026, with the conversion from petroleum refining to renewable diesel and sustainable aviation fuel feedstock processing reflecting both California’s carbon policy environment and the structural challenges facing petroleum refining economics on the West Coast.
MPLX: The Midstream Integration Advantage
The structural relationship between Marathon Petroleum and MPLX LP is the most distinctive element of Marathon’s business model relative to independent refining peers. Marathon sponsors MPLX as the general partner and largest limited partner unitholder, using the MLP to hold and operate the midstream infrastructure that supports the refinery network — crude gathering pipelines, product distribution terminals, inland marine operations, and natural gas gathering and processing assets in the Marcellus, Utica, and Permian basins.
MPLX provides Marathon with contracted midstream services under long-term agreements that include minimum volume commitments — a structure that converts variable refinery logistics costs into fixed-fee obligations while simultaneously providing MPLX unitholders with the cash flow predictability that supports consistent quarterly distributions. The integrated model reduces Marathon’s dependence on third-party logistics providers for crude supply and product distribution, improving supply chain reliability and giving the refining system margin capture at the logistics layer that standalone refiners outsource to pipeline and terminal operators.
Beyond the refinery support function, MPLX has grown into a standalone midstream business with third-party revenue streams across its gathering and processing network. Appalachian Basin gas gathering and processing — centred on the Sherwood and Harmon Creek complexes in West Virginia and Pennsylvania — generates fee income from producer customers independent of Marathon’s refining volumes, diversifying MPLX’s cash flow base and reducing the MLP’s correlation to refining margin cycles.
Marathon Petroleum Refining in the Competitive Landscape
Among the top downstream oil and gas companies globally, Marathon Petroleum occupies the second-largest independent refiner position in the US — behind Valero by throughput capacity but ahead of Phillips 66 and ahead of all other North American independent refiners. The three-way competitive dynamic between Marathon, Valero, and Phillips 66 defines the US independent refining landscape, with each company pursuing differentiated strategies around midstream integration, renewable fuels, and chemicals exposure.
Phillips 66’s midstream exposure runs through its ownership of DCP Midstream — now fully consolidated — and its NGL fractionation joint ventures, providing a midstream earnings layer comparable in strategic function to MPLX but with a different asset mix weighted toward NGL logistics rather than refinery support infrastructure. Marathon’s MPLX relationship is more deeply integrated into the refinery operating model, with a higher proportion of MPLX throughput underpinned by Marathon Petroleum minimum volume commitments.
Among the largest refineries in the world by processing capacity, Marathon’s Garyville facility at approximately 578,000 bpd ranks among the top ten single-site refineries globally — a scale that confers crude purchasing leverage, fixed-cost absorption advantages, and logistics infrastructure density that smaller refinery sites cannot match. Garyville’s deep-water access allows crude receipt from VLCC-class tankers, providing feedstock flexibility across a wider range of global crude origins than inland refineries dependent on pipeline delivery.
Renewable Fuels and Energy Transition Strategy
Marathon’s Martinez Renewable Fuels conversion — transforming the former petroleum refinery in Martinez, California, into a renewable diesel and sustainable aviation fuel production facility — is the headline energy transition investment in the portfolio. The facility processes used cooking oil, animal fats, and other biogenic feedstocks through a hydroprocessing pathway, producing renewable diesel and SAF that qualify for California LCFS credits and federal RFS compliance value.
The California location is deliberate — LCFS credit values are highest in California, and the proximity of the Martinez facility to the Bay Area and Central Valley markets reduces distribution logistics costs for California-destination renewable fuel volumes. The conversion economics depend on maintaining a credit stack — LCFS plus RFS — that supports the feedstock premium over petroleum crude at the hydroprocessing facility, a calculation that has become more competitive as renewable diesel capacity additions across North America have increased competition for low-CI feedstocks.
Sustainable aviation fuel is a longer-term growth vector at Martinez. SAF commands a premium over renewable diesel on both commodity and credit markets, reflecting aviation’s limited decarbonisation alternatives relative to road transport. Marathon has invested in SAF production capability at Martinez to capture the higher-value product slate as airline customer demand and regulatory mandates for SAF blending increase through the late 2020s.
Speedway Exit and Capital Allocation Discipline
The 2020 sale of the Speedway convenience store and retail fuel network to 7-Eleven for $21 billion was the defining capital allocation decision of the past decade for Marathon Petroleum. The transaction exited a retail business with structurally different return characteristics from refining, generated proceeds that funded an accelerated share repurchase programme, and simplified the corporate structure by removing a consumer-facing retail division from an industrial refining and midstream business.
Share repurchases funded by Speedway proceeds and subsequent free cash flow generation have reduced Marathon’s diluted share count substantially over the past four years, amplifying per-share earnings growth beyond what operating margin improvement alone would deliver. The buyback discipline — consistent with the approach of Valero and Phillips 66 across the same period — reflects the North American independent refining sector’s capital allocation philosophy of returning cash to shareholders rather than investing in capacity growth in a market where new greenfield refinery construction is not economically viable at current margins.
Marathon Petroleum — Company Snapshot
| Attribute | Detail |
|---|---|
| Full name | Marathon Petroleum Corporation |
| Ticker | NYSE: MPC |
| Headquarters | Findlay, Ohio, USA |
| Refinery count | 13 refineries |
| Total throughput capacity | ~3 million bpd |
| 2023 revenue | >$150 billion |
| Largest refinery | Garyville, Louisiana (~578,000 bpd) |
| Midstream MLP | MPLX LP (NYSE: MPLX) — ~$45bn market cap |
| Renewable fuels asset | Martinez Renewable Fuels, California |
| Retail exit | Speedway sold to 7-Eleven for $21bn (2020) |
How many refineries does Marathon Petroleum operate and where?
Marathon Petroleum operates 13 refineries across the Gulf Coast, Midwest, and West Coast of the United States, with total throughput capacity of approximately 3 million barrels per day. The largest facility is the Garyville, Louisiana refinery at approximately 578,000 bpd — one of the ten largest single-site refineries in the world. The Galveston Bay refinery in Texas City exceeds 450,000 bpd and is among the most complex refineries in the US by Nelson Complexity Index.
What is the relationship between Marathon Petroleum and MPLX?
Marathon Petroleum sponsors and controls MPLX LP as the general partner and largest limited partner unitholder. MPLX holds and operates the midstream infrastructure supporting Marathon’s refinery network — including crude pipelines, product terminals, and inland marine operations — under long-term minimum volume commitment agreements. MPLX has grown beyond refinery support to include third-party gathering and processing revenue from Appalachian Basin natural gas assets, with a market capitalisation of approximately $45 billi
How does Marathon Petroleum compare to Valero and Phillips 66?
Marathon Petroleum is the second-largest US independent refiner by throughput capacity at approximately 3 million bpd, behind Valero at 3.2 million bpd and ahead of Phillips 66 at approximately 1.8 million bpd. Marathon differentiates through the depth of its MPLX midstream integration, which is more tightly coupled to the refinery operating model than the midstream exposures of either Valero or Phillips 66. All three companies are pursuing renewable fuels investment and share repurchase programmes as their primary capital allocation priorities.
What is the Martinez Renewable Fuels facility?
The Martinez Renewable Fuels facility in Martinez, California, is Marathon Petroleum’s conversion of a former petroleum refinery into a renewable diesel and sustainable aviation fuel production plant. The facility processes used cooking oil, animal fats, and other biogenic feedstocks through a hydroprocessing pathway, producing fuels that qualify for California Low Carbon Fuel Standard credits and federal Renewable Fuel Standard compliance value. SAF production capability has been added to capture the premium product slate as airline demand and regulatory mandates for SAF blending increase.
Why did Marathon Petroleum sell Speedway and what happened to the proceeds?
Marathon Petroleum sold the Speedway convenience store and retail fuel network to 7-Eleven in 2020 for $21 billion, exiting a consumer retail business with different return characteristics from refining and midstream operations. The proceeds funded an accelerated share repurchase programme that has substantially reduced Marathon’s diluted share count, amplifying per-share earnings growth and returning capital to shareholders rather than investing in refinery capacity expansion.