The Rockies Express Pipeline (REX) has been transformative. Originally built as a west-to-east pipeline, its main job was to give Rockies natural gas a way to reach premium markets in the Midwest and the Northeast. But by the time it was constructed, surging production in the Marcellus and Utica shales had overwhelmed the need for Rockies gas in the East, and REX evolved to become a major outlet for Appalachian gas to the Midcontinent. Now, REX has moved beyond its first two incarnations, and its owner, Tallgrass Energy, has announced plans to build a greenfield pipeline that would connect REX and the markets it serves with the prolific Permian Basin, 900 miles south of the existing mainline. In today’s RBN blog, we’ll discuss REX’s history, where it stands today, and how a new pipeline connection with the Permian might fit into its evolving strategy.