But it's not just cities. Philadelphia and Baltimore and Atlanta are big cities, but they aren't the right cities. It's a small number of them. It's not just urbanism, but also brand.

True, but as someone from Europe, I can tell you the branding has always been the case. NYC, Boston, SF, and LA, were always the outstanding cities relative to those you mention above. We rarely heard of, rarely saw in movies and TV, many other cities outside of those few.

I'm not saying you're wrong -- far from it -- but the brand has been there for longer than the phenomenon we're discussing here. Perhaps the tech has just made it even more pronounced.

I think it may just depend on what it is you're trying to accomplish with your career. Take Atlanta since you bring it up. Atlanta already is the number one place to be globally for a career in Information Security which is a significant chunk of the tech community even though it's not nearly as flashy as social-web. Atlanta is also becomming a nexus for email-related startups (it's really not just Mailchimp there are several major ones here when you look at volume of email sent). Turner is headquartered in Atlanta, as is Coca Cola, Home Depot, CNN, and more.

Atlanta has become a really excellent city for graphic artists and design firms because companies such as Cartoon Network pull artists in from the global market, and then these artists stick around and end up engaging with the local startup community. In other words Atlanta is becoming a designer hub (and the city's close-enough proximity to Disney helps boost this effect)

In addition it's also a nexus for medical startups probably due to the fact that the CDC is here.

Those are good points and I don't disagree at all, but I was talking about perception more than reality. There's still this immense perception that if you're not in the top five you don't exist, and I think that's one of the factors driving real estate hyperinflation in those places.

The other funny phenomenon I've noted is people assuming we are in SV and asking whether we are "down in the valley" or "up in the city." I say "we're waaaaaay down in the valley... like eight hours South." I bet companies in Atlanta will give an address in one of Atlanta's burbs and get asked "where's that? is that in the East bay?"

Maybe the whole thing is just real estate fund or bank propaganda.

Yes, but there are others to choose from, depending on sector. Fintech startups, for example, can be based in Chicago rather than NYC, biotech has several hubs that are outside your list, etc.