The Williams Companies, Inc., together with its subsidiaries, operates as an energy infrastructure company primarily in the United States. It operates through Transmission & Gulf of Mexico, Northeast G&P, West, and Gas & NGL Marketing Services segments. The Transmission & Gulf of Mexico segment comprises natural gas pipelines; Transco, Northwest pipeline, MountainWest, and related natural gas storage facilities; and natural gas gathering and processing, and crude oil production handling and transportation assets in the Gulf Coast region. The Northeast G&P segment engages in the midstream gathering, processing, and fractionation activities in the Marcellus Shale region primarily in Pennsylvania and New York, and the Utica Shale region of eastern Ohio. The West segment consists of gas gathering, processing, and treating operations in the Rocky Mountain region of Colorado and Wyoming, the Barnett Shale region of north-central Texas, the Eagle Ford Shale region of South Texas, the Haynesville Shale region of northwest Louisiana, the Mid-Continent region that includes the Anadarko and Permian basins, and the DJ Basin of Colorado; and operates natural gas liquid (NGL) fractionation and storage facilities in central Kansas near Conway. The Gas & NGL Marketing Services segment provides wholesale marketing, trading, storage, and transportation of natural gas for natural gas utilities, municipalities, power generators, and producers; asset management services; and transports and markets NGLs. The company owns and operates 33,000 miles of pipelines. The Williams Companies, Inc. was founded in 1908 and is headquartered in Tulsa, Oklahoma.

Energy Transfer LP provides energy-related services. The company owns and operates natural gas transportation pipeline, and natural gas storage facilities in Texas and Oklahoma; and approximately 20,090 miles of interstate natural gas pipeline. It also sells natural gas to electric utilities, independent power plants, local distribution and other marketing companies, and industrial end-users. In addition, the company owns and operates natural gas gathering pipelines, processing plant, and treating and conditioning facilities in Texas, New Mexico, West Virginia, Pennsylvania, Ohio, Oklahoma, Arkansas, Kansas, Montana, North Dakota, Wyoming, and Louisiana; natural gas gathering, oil pipeline, and oil stabilization facilities in South Texas; and transports and supplies water to natural gas producer in Pennsylvania. Further, it owns 5,700 miles of natural gas liquid (NGL) pipeline; NGL fractionation facilities; NGL storage facilities; and other NGL storage assets and terminal. Additionally, the company provides crude oil transportation, terminalling, acquisition, and marketing activities; owns and operates approximately 14,500 miles of crude oil trunk and gathering pipelines in the Southwest, Midcontinent, and Midwest United States; and sells and distributes gasoline, middle distillate, and motor fuels and other petroleum products. It also offers natural gas compression services; carbon dioxide and hydrogen sulfide removal services; and manages coal and natural resources properties, as well as sells standing timber, leases coal-related infrastructure facilities, collects oil and gas royalty, and generate electrical power. The company was formerly known as Energy Transfer Equity, L.P. and changed its name to Energy Transfer LP in October 2018. Energy Transfer LP was founded in 1996 and is headquartered in Dallas, Texas.

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.

EnLink Midstream, LLC provides midstream energy services in the United States. The company operates through Permian, Louisiana, Oklahoma, North Texas, and Corporate segments. It is involved in gathering, compressing, treating, processing, transporting, storing, and selling natural gas; fractionating, transporting, storing, and selling natural gas liquids; and gathering, transporting, stabilizing, storing, trans-loading, and selling crude oil and condensate, as well as providing brine disposal services. In addition, the company's midstream energy asset network includes natural gas processing plants; fractionators; barge and rail terminals; product storage facilities; and brine disposal wells. EnLink Midstream, LLC was incorporated in 2013 and is based in Dallas, Texas.

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.

TXO Partners, L.P., an oil and natural gas company, focuses on the acquisition, development, optimization, and exploitation of conventional oil, natural gas, and natural gas liquid reserves in North America. Its acreage positions are concentrated in the Permian Basin of West Texas and New Mexico and the San Juan Basin of New Mexico and Colorado. The company was formerly known as TXO Energy Partners, L.P. and changed its name to TXO Partners, L.P. in May 2023. TXO Partners, L.P. was incorporated in 2012 and is based in Fort Worth, 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.

Mexco Energy Corporation, an independent oil and gas company, engages in the acquisition, exploration, development, and production of natural gas, crude oil, condensate, and natural gas liquids in the United States. It owns partial interests in wells located in the states of Texas, New Mexico, Oklahoma, Louisiana, Alabama, Mississippi, Arkansas, Wyoming, Kansas, Colorado, Montana, Virginia, North Dakota, and Ohio. It also owns leasehold mineral, royalty, and other interests. The company was formerly known as Miller Oil Company and changed its name to Mexco Energy Corporation in April 1980. Mexco Energy Corporation was incorporated in 1972 and is based in Midland, Texas.