Shaded by towering oaks, Gaby Valencia walked down Middlefield Road in Atherton on a sunny morning last month. When she reached the Ninth Avenue intersection, she pointed toward where the canopy gave way to weather-worn taquerias, auto shops and check-cashing storefronts.
“See how the trees just stop?” Valencia said. “That’s how you know you’re in North Fair Oaks. It’s a different world over here.”
As the Bay Area’s massive income gap widens, few places more vividly embody that chasm than the street corner locals call the “tree stop.” A Chronicle analysis of census data found that, excluding spots with universities and retirement homes, Valencia was standing near the border of the two adjacent residential areas with the region’s biggest income divide…