I've been looking all over Google and the Census Bureau's website and am having little success, although these numbers seem to be quoted in news articles and press releases so I think they're out there somewhere. Specifically I'm looking for the emigration rate for US cities (counties would be fine too). I don't want the net migration rate as that only tells me the change in population outside of births/deaths. I want to know the percentage people in a given year or decade who choose to leave a given city and move elsewhere. Anyone know where to find this data?