Swift Trail Parkway (State Route [SR] 366), an Arizona Scenic Byway, is in southeastern Arizona in Graham County ... The road begins outside Safford, at the base of Mount Graham, and continues up the mountain to Riggs Flat Lake ... Officially, the parkway's limits are milepost (MP) 116, 2.3 miles beyond the intersection of US 191 and SR 366, to MP 142. However ... the plan study area encompasses the remaining portion of road (5.8 miles) to the Riggs Flat Lake turnoff (Forest Road [FR] 287)