at Interstate 40 in Sanders. Here, US 191 has a concurrency with I-40 for from Exit 339 to Exit 333 in Chambers, where US 191 continues north through the Navajo Nation, intersecting BIA Route 28 in Klagetoh before its arrival in Ganado, where a concurrency with SR 264 begins. From there, US /SR 264 heads west past Hubbell Trading Post National Historic Site and toward Burnside, where the concurrency ends at a roundabout junction with US 191, SR 264, and BIA Route 15. At the roundabout, US 191 travels north to Chinle, where it intersects BIA Route 7, which provides access to Canyon de Chelly National Monument. Continuing north, the route intersects BIA Route 59 in Many Farms, BIA Route 12 in Round Rock, and BIA Route 35 in Rock Point, before arriving at a T-intersection with US 160 near Mexican Water. Here, US 191 shares the route with US 160 for about until it turns to the north for its final in Arizona, leaving the state at the Utah state line and entering San Juan County, heading toward Bluff. History US 191 has existed since 1926, however it did not enter Arizona at that time. With the exception of one piece built in 1981, US 191 was created in the 1980s and 90s from re-designating existing roads. The first section designated was new construction, extending from US 160 to the Utah state line across the Navajo Nation. The portion from US 160 to I-40 was originally SR 63. The portion south of I-40 was designated US 191 in 1992; it was previously U.S. Route 666. Major intersections Special routes US 191 has three special routes within the state of Arizona. Douglas business route U.S. Business Route 191 (US 191 Bus.) is a business spur of US 191 located entirely within the city of Douglas, Arizona. US 191 Bus. is long and acts as the main route into Agua Prieta in Mexico via the Douglas Port of Entry at the Mexico–United States border. Despite being a special route of US 191, US 191 Bus. never intersects with its implied parent route and instead ends at Arizona State Route 80 (SR 80) and Historic US 80 approximately east of the US 191 southern terminus. The route was previously designated as US 666 Bus. until 1992, when US 666 and all its related routes in Arizona were renumbered to extensions and special