I checked the state departments web site:
Mexico Travel Warning
Sonora: Nogales, Puerto Peñasco, Hermosillo, and San Carlos are major cities/travel destinations in Sonora - Sonora is a key region in the international drug and human trafficking trades and can be extremely dangerous for travelers. Travelers throughout Sonora are encouraged to limit travel to main roads during daylight hours. Defer non-essential travel to the region west of Nogales, east of Sonoyta, and from Caborca north (including the towns of Saric, Tubutama, and Altar), and the eastern edge of Sonora bordering Chihuahua, as these are known centers of illegal activity. Travelers should also defer non-essential travel to the eastern edge of the state of Sonora, which borders the state of Chihuahua (all points along that border east of the northern city of Agua Prieta and the southern town of Alamos), and defer non-essential travel within the city of Ciudad Obregon and south of the city of Navojoa. You should exercise caution while transiting Vicam in southern Sonora due to roadblocks that can be instituted ad hoc by local indigenous and environmental groups. U.S. citizens visiting Puerto Peñasco should use the Lukeville, Arizona/Sonoyta, Sonora border crossing, and limit driving to daylight hours. Please see above for general conditions for travel in Mexico.