The decrease was mainly caused by the closure of LyondellBasell’s Houston refinery and Phillips 66’s Los Angeles refinery, which together removed about 400,000 b/d of capacity. Some of this loss was offset by small efficiency improvements and expansions at other refineries. The West Coast was more affected because limited pipeline connections make it harder to replace lost refining capacity with supplies from other regions.
The report shows that major US refiners, including Marathon, Valero, and ExxonMobil, made only minor capacity increases, while Phillips 66 declined due to refinery closures. Motiva’s Port Arthur refinery remains the largest US refinery by calendar-day capacity, while Marathon’s Galveston Bay refinery remains the largest by maximum operating capacity.
The US refining sector entered 2026 with slightly reduced capacity, reflecting refinery closures, limited expansions, and regional supply challenges.
