After a decade of hyperactive growth, America's tech hubs now are in danger of sharp reversals.
It may seem like a distant memory, but downtown San Francisco was still largely a financial center only 10 years ago, when its conversion into a bro-dominated tech capital of the universe wasn't yet in full bloom. Back then, the tech industry was known for being dispersed across the suburban towns of Silicon Valley, and venture capitalists famously lined Sand Hill Road in Menlo Park.
