Park Valley is an unincorporated community in Box Elder County, Utah, United States.Park Valley lies in the northwestern part of the state, 150 miles northwest of the state capital at Salt Lake City, and 100 miles west of the county seat at Brigham City. Utah State Route 30 runs through the center of the valley, generally from east to west. The valley is a roughly oval shape of about 30 miles in length east to west and about 25 miles north to south, covering a major portion of the western end of the county.Park Valley anchors the northern end of the Great Basin. The Raft River Mountains to the north mark the boundary between the Great Basin and the Snake River Plain.