Two potential explanations spring to mind. One is that there was a structural shortage of skilled workers at the national level, and immigration rules prevented movement from abroad to clear the market. Another is that housing markets responded insufficiently to the demand for shelter in the Silicon Valley area, causing housing costs to rise too high to accommodate new workers. At the height of the tech boom, in 1999, the entire San Francisco-Oakland-San Jose metroplex approved permits for just 26,000 new housing units. In the same year, tiny Las Vegas approved 28,000. Atlanta approved over 60,000. Tight supply fueled high prices. From 1996 to 2001, home prices in San Francisco rose by more than they did during the 2002-2006 bubble. With housing costs soaring, it took very high wages to attract scarce workers. Entrepreneurship seems to have suffered as a result.