Marathon Petroleum Corporation, together with its subsidiaries, operates as an integrated downstream energy company primarily in the United States. The company operates through Refining & Marketing, and Midstream segments. The Refining & Marketing segment refines crude oil and other feedstocks at its refineries in the Gulf Coast, Mid-Continent, and West Coast regions of the United States; and purchases refined products and ethanol for resale and distributes refined products, including renewable diesel, through transportation, storage, distribution, and marketing services. Its refined products include transportation fuels, such as reformulated gasolines and blend-grade gasolines; heavy fuel oil; and asphalt. This segment also manufactures propane and petrochemicals. It sells refined products to wholesale marketing customers in the United States and internationally, buyers on the spot market, and independent entrepreneurs who operate primarily Marathon branded outlets, as well as through long-term fuel supply contracts to direct dealer locations primarily under the ARCO brand. The Midstream segment transports, stores, distributes, and markets crude oil and refined products through refining logistics assets, pipelines, terminals, towboats, and barges; gathers, processes, and transports natural gas; and gathers, transports, fractionates, stores, and markets natural gas liquids. Marathon Petroleum Corporation was founded in 1887 and is headquartered in Findlay, Ohio.

Targa Resources Corp., together with its subsidiary, Targa Resources Partners LP, owns, operates, acquires, and develops a portfolio of complementary domestic midstream infrastructure assets in North America. It operates in two segments, Gathering and Processing, and Logistics and Transportation. The company is involved in gathering, compressing, treating, processing, transporting, and selling natural gas; storing, fractionating, treating, transporting, and selling natural gas liquids (NGL) and NGL products, including services to liquefied petroleum gas exporters; and gathering, storing, terminaling, purchasing, and selling crude oil. It is also involved in the purchase and resale of NGL products; and sale of propane, as well as provision of related logistics services to multi-state retailers, independent retailers, and other end-users. In addition, the company offers NGL balancing services; and transportation services to refineries and petrochemical companies in the Gulf Coast area, as well as purchases, markets, and resells natural gas. As of December 31, 2023, it leased and managed approximately 605 railcars; 137 tractors; and 6 vacuum trucks and 2 pressurized NGL barges. Targa Resources Corp. was incorporated in 2005 and is headquartered in Houston, Texas.

Plains All American Pipeline, L.P., through its subsidiaries, engages in the pipeline transportation, terminaling, storage, and gathering of crude oil and natural gas liquids (NGL) in the United States and Canada. The company operates through two segments, Crude Oil and NGL. The Crude Oil segment offers gathering and transporting crude oil through pipelines, gathering systems, trucks, and on barges or railcars. This segment provides terminaling, storage, and other facilities-related services, as well as merchant activities. The NGL segment is involved in natural gas processing and NGL fractionation, storage, transportation, and terminaling. This segment also includes ethane, propane, normal butane, iso-butane, and natural gasoline derived from natural gas production and processing activities, as well as crude oil refining processes. Its NGL components are used for various applications, such as heating, engine, and industrial fuels. The company was founded in 1981 and is headquartered in Houston, Texas. Plains All American Pipeline, L.P. operates as a subsidiary of Plains GP Holdings, L.P.

Plains GP Holdings, L.P., through its subsidiary, Plains All American Pipeline, L.P., owns and operates midstream infrastructure systems in the United States and Canada. It operates in two segments, Crude Oil and Natural Gas Liquids (NGLs). The company engages in the gathering and transporting crude oil and NGLs using pipelines, gathering systems, and trucks. It engages in the loading and unloading services at terminals; NGL fractionation and isomerization services; and natural gas and condensate processing services. The company offers logistics services to producers, refiners, and other customers. PAA GP Holdings LLC operates as a general partner of the company. Plains GP Holdings, L.P. was incorporated in 2013 and is headquartered in Houston, Texas.

Delek Logistics Partners, LP provides gathering, pipeline, transportation, and other services for crude oil, intermediates, refined products, natural gas, storage, wholesale marketing, terminalling water disposal and recycling customers in the United States. The Gathering and Processing segment consists of pipelines, tanks, and offloading facilities that provide crude oil and natural gas gathering and processing, water disposal and recycling, and storage services, as well as crude oil transportation services to third parties. The Wholesale Marketing and Terminalling segment includes refined products terminals and pipelines in Texas, Tennessee, and Arkansas. This segment provides marketing services for the refined products and terminalling services at refined products terminals to independent third parties. The Storage and Transportation segment comprises tanks, offloading facilities, trucks, and ancillary assets, which provide crude oil, intermediate, and refined products transportation and storage services. Delek Logistics GP, LLC serves as the general partner of the company. Delek Logistics Partners, LP was incorporated in 2012 and is headquartered in Brentwood, Tennessee. Delek Logistics Partners, LP operates as a subsidiary of Delek US Holdings, Inc.

NGL Energy Partners LP engages in the transportation, storage, blending, and marketing of crude oil, natural gas liquids, refined products/renewables, and water solutions. The company operates through three segments: Water Solutions, Crude Oil Logistics, and Liquids Logistics. The Water Solutions segment transports, treats, recycles, and disposes produced and flowback water generated from crude oil and natural gas production; aggregates and sells recovered crude oil; disposes solids, such as tank bottoms, and drilling fluid and muds, as well as performs truck and frac tank washouts; and sells produced water for reuse and recycle, and brackish non-potable water. The Crude Oil Logistics segment purchases crude oil from producers and marketers, and transports it to refineries for resale at pipeline injection stations, storage terminals, barge loading facilities, rail facilities, refineries, and other trade hubs; and provides storage, terminaling, and transportation services through pipelines and storage tanks. The Liquids Logistics segment supplies natural gas liquids, refined petroleum products, and biodiesel to commercial, retail, and industrial customers in the United States and Canada through its 23 terminals, third-party storage and terminal facilities, and nine common carrier pipelines, as well as through a fleet of leased railcars. This segment also provides services for marine exports of butane through its facility located in Chesapeake, Virginia; and owns a propane pipeline in Michigan. NGL Energy Holdings LLC serves as the general partner of the company. The company was founded in 1940 and is headquartered in Tulsa, Oklahoma.

Martin Midstream Partners L.P., together with its subsidiaries, provides terminalling, processing, storage, and packaging services for petroleum products and by-products primarily in the United States. The company operates in four segments: Terminalling and Storage, Transportation, Sulfur Services, and Specialty Products. The company's Terminalling and Storage segment owns or operates various marine shore-based terminal facilities and specialty terminal facilities that provide storage, refining, blending, packaging, and handling services for producers and suppliers of petroleum products and by-products. This segment also offers land rental services to oil and gas companies, as well as storage and handling services for lubricants and fuels. Its Transportation segment operates various trucks and tank trailers; and inland marine tank barges, inland push boats, and articulated offshore tug and barge unit to transport petroleum products and by-products, petrochemicals, and chemicals. The company's Sulfur Services segment processes molten sulfur into prilled or pelletized sulfur, which is used in the production of fertilizers and industrial chemicals. Its Specialty Products segment stores, distributes, and transports natural gas liquids for wholesale deliveries to refineries, industrial natural gas liquid users, and propane retailers. Martin Midstream GP LLC serves as a general partner of the company. Martin Midstream Partners L.P. was incorporated in 2002 and is based in Kilgore, Texas.

Summit Midstream Partners, LP focuses on owning, developing, and operating midstream energy infrastructure assets primarily shale formations in the continental United States. The company provides natural gas gathering, compression, treating, and processing services, as well as crude oil and produced water gathering and freshwater delivery services. Its assets include Summit Utica system comprising the Utica and Point Pleasant shale formations in southeastern Ohio; Mountaineer Midstream system that includes the Marcellus shale in the Appalachian Basin in West Virginia; Polar and Divide system includes the Bakken and Three Forks shale formations in northwestern North Dakota; Niobrara G&P system, which comprises the Niobrara and Codell shale formations located near Hereford, Colorado. The company's assets also include Double E, a 135 mile interstate natural gas transmission pipeline; Grand River system that gathers natural gas produced from the Mancos and Niobrara shale formations in western Colorado; and DFW Midstream system comprising the Barnett Shale formation located in north-central Texas. In addition, it owns an ownership interest in Ohio Gathering, which owns and operates natural gas gathering and condensate stabilization facility in the Utica Shale in southeastern Ohio. It serves natural gas and crude oil producers. Summit Midstream GP, LLC operates as a general partner of the company. Summit Midstream Partners, LP was founded in 2009 and is based in Houston, Texas.