The Appalachian Basin, encompassing the Marcellus and Utica Shale formations across Pennsylvania, Ohio, and West Virginia, is a leading natural gas producer, with an average output of 31.7 billion cubic feet per day in 2021. In 2023, top operators include EQT Corp. (859,302 boe/d), Chesapeake Energy (727,286 boe/d), Antero Resources (455,453 boe/d), Southwestern Energy (441,111 boe/d), and Coterra Energy. At the start of 2023, the daily production was 6,15 million BOE per day and decreased to 4,88 million BOE per day as of December 2023.