Arizona Bus and Shuttle Services
It used to be that if you wanted to take commercial ground transportation to Sonora, you needed to take a bus or shuttle to the border, cross the border on foot and then take a taxi to a Mexican bus station.
And while that option is still available, you can now take a bus from Phoenix or Tucson to destinations in Mexico. You will still need to go through Mexican customs at the border, but you can then re-board the bus and continue on your journey.
There are also travel companies that offer bus tours to destinations in Sonora, and if you want to organize a group and charter a bus to Puerto Penasco or some other Sonoran destination, there are Arizona motorcoach charter companies that provide that service as well.
Bus Service from Arizona to Mexico
Sonora Bus Tours
Charter a Motorcoach to Sonora
Mexico Border Shuttles