What the Census Bureau describes as "outflows," or folks who move from one county to another. In a new report that covers the years from 2005 to 2009, L.A. County had the highest number of people leaving for another county and the highest number of people entering from another county. On balance, however, L.A. loses a net of 160,000 people in the exchange. From release:
All in all, the most common county-to-county moves nationally were from Los Angeles to San Bernardino, Calif. (48,456 people) and Los Angeles to Orange, Calif. (41,612). Los Angeles to Riverside, Calif. (29,710); Orange, Calif., to Los Angeles (29,345); and Miami-Dade to Broward, Fla. (27,010) were among the next most common county-to-county moves.