Ask HN: What is a security clearance worth?

I currently live in DC, and the possibility to get a security clearance is opening up to me. I still have high hopes of moving to Silicon Valley once I'm done with my PhD, but if I stick around for an extra few months and submit to questioning, a clearance could be had. Its value in the DC area is somewhat obvious (and huge, actually), but how valuable is it elsewhere, especially tech-heavy places like Silicon Valley, SF, Austin, etc.?