U.S. Route 191 (US 191) is a north–south United States Highway within Arizona. The highway runs for , the longest of any numbered highway in Arizona, from State Route 80 near Douglas to the Utah state line near Mexican Water. As it crosses the state, US 191 overlaps at various points: I-10, US 70, US 180, US 60, SR 61, I-40, SR 264, and US 160. Previously the route was designated as US 666 and SR 63. Route description Douglas to Safford The national southern terminus of US 191 is located at an intersection with SR 80 west of Douglas, in Cochise County. It heads north from this junction, past Bisbee Douglas International Airport and then through the unincorporated communities of McNeal and Elfrida before passing by Sunizona and the western terminus of SR 181, which provides access to Chiricahua National Monument. The road curves west and heads toward Sunsites, where it turns to the northwest and passes by the community of Cochise with a bridge over the Union Pacific Railroad. Continuing northwest, US 191 meets Interstate 10 at Exit 331, a trumpet interchange, and has a concurrency with I-10 for about . Heading northeast, I-10/US 191 passes around Willcox, with three exits serving the town: Exit 336, which is the southwestern end of the Willcox I-10 Business Loop; Exit 340, which is the northern terminus of SR 186; and Exit 344, which serves as the northern end of the Business Loop. Northeast of Willcox, US 191 leaves I-10 at Exit 352 and heads north toward Safford, leaving Cochise County and entering Graham County along the way. Just north of I-10, US 191 passes through an intersection with Page Ranch Road, officially designated as US 191 Wye . This provides a shortcut for traveling between Bowie and Safford, as the mainline of US 191 is curved toward the west near I-10. Going toward Safford, the eastern terminus of two state routes intersect the route, namely SR 266, which provides access to Fort Grant, and SR 366 in Swift Trail Junction, which climbs up to the summit of Mount Graham and provides access to Mount Graham International Observatory. Arriving in Safford, US 191 turns east at an intersection with 5th Street (US 70), where its concurrency with US 70 begins. Safford to St. Johns Traveling east from Safford, US 70/US 191 passes by the communities of Solomon and San Jose before