There are two main routes from Phoenix to Tucson. Straight down I 10 which will take about 2 hours or the back road route via US 60 E and Florence which will take about 45 minutes longer. A third option is to continue East to Globe then taking US 77 South to Oracle Junction. This route traverses some great Sonoran Desert scenery but this will take much longer, more than 4 hours.
If you opt to take the interstate there are some points of interest along the way.
Picacho Peak State Park
Rising to the West of the highway the peak is easily spotted. An entrance fee is charged and there is a good visitor centre with a selection of books, maps and souvenirs. There are a number of hiking trails ranging from moderate to difficult and also a short and level nature trail. The park is currently closed seasonally from May to September.
Casa Grande Ruins National Monument
This is a short drive to the East of I 10 close to Coolidge. The site preserves the remains of a Great House constructed by the ancient Sonoran Desert people. The purpose of the building is unknown but would have been a central point for the community. A ball court can also be seen here just as is the case at Pueblo Grande in Phoenix.
Pinal Air Park
You can’t visit this location but you can get a glimpse of rows of aircraft tails from the highway. The airpark is used for the short and long term storage of commercial aircraft that are mothballed pending their next use. The Sonoran desert climate is ideal for the storage of aircraft.
US 60 E
Boyce Thompson Arboretum
If you take this route it is worth continuing East past the junction with US 79 to visit the Boyce Thompson Arboretum. Run by the University of Arizona the Arboretum contains not just the plants of this region but also species from all over the world including trees from Australia. There is of course a substantial cactus garden. A gentle loop trail runs round the site and passes by all of the key areas. Whilst much of the garden is exposed to the full heat of the sun there are also many shaded areas. I’d allow at least 2 hours for a visit here.
The visitor centre at the entrance has a small store that sells a large selection of cacti and succulents. You can also replenish your water bottles here.
If you need to stock up with supplies or food before continuing there is a Circle K in the small town of Superior is just a little bit further West.
Casa Grande can also easily be visited if you backtrack and take US 79 South.
Now owned by the University of Arizona the biosphere was originally constructed to research the functioning of ecosystems. Famously the first 2 “missions” involved a human crew who had to survive within the sealed, self sustaining ecosystem subsisting on the produce grown inside.
The Biosphere can be visited on guided tours that take place throughout the day. You get to see the areas that were occupied by the crew and also each of the habitats in the ecosystem including the Ocean and the Tropical Rainforest. All in all and interesting way to spend an hour or so.