A funny thing. Here in Colorado, we're constantly deluged with the idea that everyone from California is constantly packing up their bags and moving here.
With this map from Forbes, however, we may have to change the "g" in deluged with a "d".
It shows the inter-county movement of people in the year 2008. Fully interactive, you can click on any county you so choose. I happened to check the Denver area counties of Denver, Adams, Arapahoe, Douglas, and Jefferson. The results are plain: more people from this area are moving to California than moving here from California.
Click your way around. It is truly fascinating. And, of course, the data is from the IRS, so take advantage of your tax dollars while you can.