SAN JOSE, Calif. -- Silicon Valley is entering a fifth year of unfettered growth. The median household income is $90,000. The average single-family home sells for about $1 million. The airport is adding a multimillion-dollar private jet centre.

But the river of money flowing through America's tech mecca has also driven housing costs to double while wages for low- and middle-skilled workers are stagnant. Now the widening income gap between the wealthy and those left behind is sparking debate, anger and sporadic protests.

Some even with jobs get supplies from a food bank. Rants against the 1 per cent are spray-painted on buildings in wealthy towns. Security guards rally outside Apple Inc. demanding better wages with a banner that reads: "What's the matter with Silicon Valley? Prosperity for some, poverty for many. That's what."