State Route 78 (Arizona–New Mexico) State Route 78 (Arizona–New Mexico) Arizona State Route 78 (SR 78) and New Mexico State Road 78 (NM 78) are a pair of adjoining state highways located in eastern Arizona and western New Mexico linking U.S. Route 191 (US 191) and Arizona State Route 75 near Greenlee County Airport to US 180 northwest of Cliff, New Mexico. It is also known in its Arizona stretch as Mule Creek Road. The western terminus of SR 78 is located at a junction with US 191 and SR 75 at Three Way, Arizona near Greenlee County Airport. The highway heads northeast from this
Arizona State Route 143 Interstate 10 and US 60 between the Mini Stack and the Broadway Curve, adding to additional traffic overload and safety issues at the interchange with SR 143/I-10/US 60. The speed limit on I-10 throughout the city of Phoenix is currently . Many other area freeways have limits of , notable exceptions being the Sky Harbor Expressway with , Arizona 51 south of Glendale Rd with 55 mph, and Interstate 17 with . Arizona State Route 143 Arizona State Route 143, also known as SR 143 and the Hohokam Expressway, is a north–south and access-controlled freeway in Maricopa County, Arizona, that