The San Pedro comes through Mammoth under a ribbon of cottonwoods, and on a June morning that is the coolest air in the valley. Green Thumb Lawn Service works early, cutting yards while the shade is still on them and the day has not yet turned to a furnace. The passes go even, the trimmer follows the walls and posts, and the clippings come off the walk instead of tracking into the house. In an old copper town tucked between the river and the hills, a mowed lawn is a small green flag: somebody is here, somebody is tending it. That is worth doing right every week.