While Googlers are spread across most of the northern California landscape, the densest populations live in these two areas, according to a recent report commissioned by Google.
The explanations aren't hard to deduce.
The neighborhood of North Bayshore (in Mountain View) hugs the company's main headquarters, the Googleplex campus.
Venture outside the Mountain View area, however, and most of Silicon Valley doesn't get interesting until you hit the city by the bay.
As Google sees it, the valley has a major commuter problem on its hands: people are driving too much.
According to research Google conducted alongside Alta Planning + Design, only 21% of employees living within nine miles of Google bike to work. For all employees, the rate drops to 9%.
That disparity is a far cry from the two-wheeled culture inside the Googleplex, where yellow-framed bikes can be seen gliding past at all hours.
It's part of the company's mission to reduce the reliance on cars, especially for people who spend most of their driving time alone.
As a potential solution, Google is offering up $5 million in grant money to surrounding cities in Silicon Valley if they come up with clever ideas for how to make their neighborhoods more bike-friendly.
Ultimately, the hope is to mimic the success of European biking programs, which have been widely touted as the gold-standard.
In Copenhagen, for example, roughly half the city commutes to school or work via bicycle. The preference for bikes is so high that bike lanes are cleared before roadways after big snowstorms.