The Sonoran Desert is the only North American desert with trees that can actually make a canopy. The mesquite and the foothills palo verde, given a hundred years and a little water, will close over a street. The University of Arizona’s main mall and the adjacent Sam Hughes neighborhood were planted with both in the 1930s and 40s, and the result — three-quarters of a century later — is a square mile of central Tucson that walks ten degrees cooler than the rest of the city.
The picks below are all on or just off the main campus mall. The mall itself is a wide grass spine running east from Old Main, lined with mesquites that have grown together overhead in a kind of low arched cover. East of Campbell, the residential streets in Sam Hughes hold the same canopy on a smaller scale — narrower lots, more shade per foot. The trick on these walks is to commit to the east–west streets. The north–south ones are too wide to canopy.