It's surprising to me that so many in this thread are asking if these rankings are legit. Of course they aren't -- they operate on a simplification that trade accuracy for convenience. It's one developer's side project...many professional companies and analysts have failed to encapsulate the worth of a human being as a number, why should this developer be any better? That said, I imagine a lot of headhunter companies…
I live in Columbia Missouri (MO) and the rankings for "Columbia" include folks from Columbia Maryland (MD) and Columbia South Carolina (SC).
So even if people want to use dashboard summary data like this, they should do some basic validation to figure out what the data means and how it was analyzed (and what flaws it might entail).