[subhash]

You seem to be considering only cities in the US because it doesn't seem practical to ask startups to move across countries, especially if they are very different. As a corollary, a city might benefit instead by exploiting the local peculiarities to espouse a startup culture.

For example, in the city I live in, it's perfectly acceptable to live with your parents all your life. And that's a perfect fit for lowering living costs. There is also an obsession to live in or close to your hometown, which might force college grads to start up instead of working for a big company in a big city. There is a strong sense in society of admiring entrepreneurship as opposed to employment because of a (convoluted) communistic ideal. There is a lot of investment money readily available from expatriates from the Middle East that they cannot use in their country of residence.

This might mean that there is a different route to becoming Silicon Valley and it is all the more difficult to determine because it is not generic.