Arizona is such a sprawled out state that a car is really necessary to have the freedom to make the most of your time in Arizona. Arizona is not known for an awesome mass transit system. Phoenix does offer Valley Metro Bus and the New Light Rail System, which has stops between Phoenix and Mesa and plans on expanding in the future. Right now you can take the Light Rail System to see the Heard Museum, Arizona Center, ASU Downtown Phoenix, Arizona Science Center, the Convention Center, Tempe Town Lake, and Sun Devil Stadium.

Tucson area has the Sun Tran, Flagstaff has the Mountain Rail, and Sedona has Roadrunner for mass transit city bus services.

Major interstates include:

Interstate-17 which runs north and south from Flagstaff down to about Tempe. Also known as Black Canyon Freeway
Interstate-10 which continues from Phoenix South to Tucson, West to LA and from Tucson can be taken to New Mexico. Also known in Phoenix as the Papago Freeway. Tucson is experiencing major reconstructing of this one and only freeway that runs through the city. If you are visiting Tucson, check out the I-10 Construction Updates.
Loop 101 loops several suburbs together running west of Phoenix in Avondale, North to Glendale, East through Peoria, Scottsdale and then south to Chandler. Also known as the Agua Fria Freeway
Loop 202 runs east of Phoenix through the suburbs of Mesa, Also known as Red Mountain Freeway
Loop 303 is still in the process of being built in the Northwest Valley Also known as the Estrella Freeway
State Route 51 runs north and south connecting Interstate 10 in downtown Phoenix with the Loop 101 on the north side of Phoenix. Also known as Piestewa Peak Parkway it runs along the mountain range with the same name. A pretty drive in my opinion.
State Route 60 goes east of Phoenix through Mesa, Apache Junction and west of Phoenix through Glendale, Peoria, and all the way to Vegas.

In Phoenix:

Streets are east of Central Ave, Avenues are west of Central.
Phoenix freeways utilize many ramp meters during rush hour.

Interstate 8 runs from Casa Grande to Yuma

Interstate 40 runs east to west from California through Flagstaff and on to New Mexico. I-40 replaced famous Route 66, with the exception of the stretch between Kingman and Flagstaff.

Airline

Phoenix Sky Harbor International Airport is the major airport in the state of Arizona. It is in the top ten busiests airports in the U.S.A.

Twenty three airlines are represented here with over 100 Domestic non-stop flights per day leaving Sky Harbor.

There are three terminals Terminal 2, Terminal 3, and Terminal 4

Tucson International Airport has 11 airlines that fly in and out of Tucson.