It has an interactive map showing the steady westward march of the center of population along with a map of the states in the union. Another way to waste a few minutes.
I'm somewhat surprised it isn't further west. As a midwesterner turned west coast resident, I keep getting the feeling that there's more people here than there really are. It doesn't help that alot of the tech/hacker community is west coast based, or at least the most vocal/prominent folks anway.
You'd think I'd know that considering I used to live in Denver and drive a truck all over the US (coast to coast). I now how remote the west can be, like the stretches between Green River and Ritchfield Utah, or Needles to Barstow, CA. Still seems surprisingly far east though.
It seems to me it's a very flawed metric since one person in San Diego has a far greater influence on the center than someone in Oklahoma due to the leverage calculation.