Why does demand for housing in the San Francisco Bay Area keep growing? High-tech innovation benefits from existing networks and close proximity to other tech firms. According to a recent report by the Brookings Institute, since 2005 five metropolitan areas have accounted for 90% of all growth in United States in the innovation sector (which includes science, technology and engineering industries). The San Francisco Bay Area,San Jose, Seattle, Boston and San Diego are reaping the benefits of this economic growth and wealth accumulation. A result is that buyer demand is concentrated in a handful of top tier cities. With the forces at play unlikely to disappear anytime soon, real estate in these cities looks like a good bet.