What is the name of the freeway that runs through the heart of Silicon Valley?

U.S. Route 101 is the freeway most commonly identified as running through the heart of Silicon Valley.

In the Bay Area, US 101 is a major north–south transportation corridor linking San Jose with the Peninsula and San Francisco. Its Silicon Valley segment passes through or near technology centers including Mountain View, Palo Alto, Redwood City, and San Mateo. In different sections it is known as the Bayshore Freeway or South Valley Freeway.

The route is especially important because it follows the urbanized western side of San Francisco Bay, where many technology campuses and dense employment centers developed. It carries heavy commuter traffic and connects the South Bay to the wider Bay Area, making it a practical backbone of Silicon Valley even though the region has several major freeways.

The main alternative people may name is Interstate 280. I-280 runs roughly parallel to US 101, generally farther west along the foothills of the Santa Cruz Mountains, and is also an important Silicon Valley route. Interstate 880 serves the East Bay, while California State Route 85 forms a more local beltway. The quiz’s canonical answer is therefore US 101.