The map below shows the latest results from a Forbes study, using IRS data, on where Americans moved from one county to another during the year 2008. I specifically picked Brookings, South Dakota and I was not surprised to see more of comings than goings. This is most likely due to the influx of students to the county. The South Dakota State University in Brookings is the largest university in the state.
The map looks crappy and no numbers were given. But this is enough to give us a general idea of the migration happening in Brookings.
Source: Internal Revenue Service data. The IRS only reports inter-county moves for more than 10 people, so some moves are not shown on this map. Black lines indicate net inward movement, red lines net outward movement.