There are two major roads that run through town: Milton Road and Route 66 (new Route 66). Milton turns into new Route 66. The two roads run through the main parts of town and will take you almost anywhere you need to go. Beware: the two roads do get heavy traffic in the mornings and late afternoons. If you want to avoid the traffic, take Interstate 40 around town or use old Route 66 instead of Milton.
You can fly into two airports. The first (and closest) is Pulliam Airport, just 5 miles outside of town. The second is Sky Harbor International Airport in Phoenix, Arizona; it is roughly 130 miles from Flagstaff. There is a shuttle ($38.00 if you purchase a ticket online) that will take you from Sky Harbor to the Flagstaff Visitor’s Center.
You can explore a lot of Flagstaff on foot or by bus. The town is small and it works out very well for tourists. However, if you want to do extra excursions to places around Flagstaff (such as Snowbowl, Sunset Crater, Grand Canyon or any of the lakes) you will need to rent a car or join a guided tour group.