Given that the saguaro cactus only grows in the wild in the Sonoran Desert and that the mountains around Phoenix are covered with them all you gotta do is to find the nearest spot on the American /Mexican border to Phoenix and do the mathLukeville AZ by Organ Pipe National Monument is bordertown that is about 150 miles away @ 30 mpd it s a 6 day walk.....carry water .....and drink it
Gaging it from the Sonoran Desert National Monument to central Phoenix it is 55 miles and in a car it is just over an hour drive. It would seem that you could walk it in about 17 hours following the car route. A straight shot would be harder because of the mountains you would have to climb.
Where in the Sonoran Desert? 75% of Arizona is in the Sonoran Desert as are parts of California and New Mexico.