HollyFrontier Corporation is an independent petroleum refiner in the United States. The Company produces refined products, such as gasoline, diesel fuel, jet fuel, lubricant products, and specialty and modified asphalt. The Company operates through two segments, namely, Refining and HEP. The Refining segment includes the operations of its El Dorado, Tulsa, Navajo, Cheyenne and Woods Cross Refineries, and NK Asphalt Partners (NK Asphalt). The Company’s refinery operations serve the Mid-Continent, Southwest and Rocky Mountain regions of the United States. The HEP segment includes of the operations of the Company’s subsidiary Holly Energy Partners, L.P. (HEP). HEP is a limited partnership that acquires, owns and operates of the refined product pipeline and terminalling assets that support the refining and marketing operations in the Mid-Continent, Southwest and Rocky Mountain regions of the United States.