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.

MPLX LP owns and operates midstream energy infrastructure and logistics assets primarily in the United States. It operates in two segments, Logistics and Storage, and Gathering and Processing. The company is involved in the gathering, processing, and transportation of natural gas; gathering, transportation, fractionation, storage, and marketing of natural gas liquids; gathering, storage, transportation, and distribution of crude oil and refined products, as well as other hydrocarbon-based products and renewables; and sale of residue gas and condensate. It also engages in the inland marine businesses comprising fleet of boats and barges transportation of light products, heavy oils, crude oil, renewable fuels, chemicals, and feedstocks in the Mid-Continent and Gulf Coast regions, as well as a marine repair facility located on the Ohio River; and distribution of fuel, as well as operates refining logistics, terminals, rail facilities, and storage caverns. In addition, the company operates terminal facilities for the receipt, storage, blending, additization, handling, and redelivery of refined petroleum products through the pipeline, rail, marine, and over-the-road modes of transportation. MPLX GP LLC acts as the general partner of MPLX LP. The company was incorporated in 2012 and is headquartered in Findlay, Ohio. MPLX LP operates as a subsidiary of Marathon Petroleum Corporation.

Western Midstream Partners, LP, together with its subsidiaries, operates as a midstream energy company primarily in the United States. It is involved in gathering, compressing, treating, processing, and transporting natural gas; gathering, stabilizing, and transporting condensate, natural gas liquids (NGLs), and crude oil; and gathering and disposing produced water. The company also buys and sells natural gas, NGLs, and condensate. It operates assets located in Texas, New Mexico, the Rocky Mountains, and North-central Pennsylvania. Western Midstream Holdings, LLC operates as the general partner of the company. The company was formerly known as Western Gas Equity Partners, LP and changed its name to Western Midstream Partners, LP in February 2019. Western Midstream Partners, LP was incorporated in 2007 and is based in The Woodlands, 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.

Hess Midstream LP owns, develops, operates, and acquires midstream assets and provide fee-based services to Hess and third-party customers in the United States. It operates through three segments: Gathering; Processing and Storage; and Terminaling and Export. The Gathering segment owns natural gas gathering and compression systems; crude oil gathering systems; and produced water gathering and disposal facilities. Its gathering systems consists of approximately 1,410 miles of high and low pressure natural gas and natural gas liquids gathering pipelines with capacity of approximately 660 million cubic feet per day; crude oil gathering system comprises approximately 570 miles of crude oil gathering pipelines; and produced water gathering system that includes approximately 300 miles of pipelines in gathering systems. The Processing and Storage segment comprises Tioga Gas Plant, a natural gas processing and fractionation plant located in Tioga, North Dakota; a 50% interest in the Little Missouri 4 gas processing plant located in south of the Missouri River in McKenzie County, North Dakota; and Mentor Storage Terminal, a propane storage cavern and rail, and truck loading and unloading facility located in Mentor, Minnesota. The Terminaling and Export segment owns Ramberg terminal facility; Tioga rail terminal; crude oil rail cars; and other Dakota access pipeline connections, as well as Johnson's Corner Header System, a crude oil pipeline header system. Hess Midstream LP was founded in 2014 and is based in Houston, 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.

Summit Midstream Corporation focuses on owning, developing, and operating midstream energy infrastructure assets primarily shale formations in the continental United States. It operates natural gas, crude oil, and produced water gathering systems in four unconventional resource basins, including the Williston Basin in North Dakota, which includes the Bakken and Three Forks shale formations; the Denver-Julesburg Basin that consists of the Niobrara and Codell shale formations in Colorado and Wyoming; the Fort Worth Basin in Texas, which comprises the Barnett Shale formation; and the Piceance Basin in Colorado, which includes the Mesaverde formation, as well as the emerging Mancos and Niobrara Shale formations. It serves natural gas and crude oil producers. Summit Midstream Corporation was founded in 2012 and is based in Houston, Texas.