US refinery capacity is not uniformly distributed geographically, and individual refineries are optimized for specific crude slates and product mixes. Certain regions — particularly the Northeast — rely heavily on imported refined products because local refining capacity is insufficient to meet demand, and pipeline infrastructure limits product movement from Gulf Coast refineries.

Petroleum coke (petcoke) is a solid carbon byproduct of the refining process and is classified separately from liquid refined products under the HTS. It is traded as a fuel and industrial feedstock, with calcined petcoke used in aluminum smelting and electrode manufacturing. Importers should confirm whether the petcoke is calcined or uncalcined, as this distinction affects HTS classification and applicable duty rates.