headquartered in findlay, ohio, marathon petroleum corporation (mpc), together with its subsidiaries, including marathon petroleum company lp and speedway llc, is one of the largest petroleum product refiners, marketers and transporters in the united states. mpc is the nation’s fourth-largest refiner and the largest refiner in the midwest. mpc’s refining, marketing and transportation operations are concentrated primarily in the midwest, gulf coast and southeast regions of the u.s. mpc operations are strategically located to serve major markets. they include a seven-plant refining network, a comprehensive terminal and transportation system, and extensive wholesale and retail marketing operations. this includes both the marathon brand and mpc’s wholly-owned retail marketing subsidiary, speedway llc, the nation’s fourth-largest chain of company-owned and -operated retail gasoline and convenience stores.