Some other interesting facts from this 2007 commuter inflow-outflow data:
- Minnehaha County has the largest commuter outflow by dollar, with commuters taking $1.26 billion out of Minnehaha in 2007. Minnehaha commuters import $359 million.
- Where's all that Sioux Falls money go? Look south of 57th Street: Minnehaha's neighbors in Lincoln County import 54.7% ($834 million) of their county income. Lincoln does also support a lot of out-of-town commuters, exporting $275 million in wages.
- Shannon, Todd, and Buffalo counties have the highest ratios of outflow to inflow. Commuters from elsewhere take $20 out of Shannon County for every $1 Shannon County commuters bring in.
- One clear correlation I notice is between the net flow (inflow minus outflow) and population: the fewer people in a county, the more likely that county is to import more wages than it exports. The more people, the more outflow. This is probably obvious: more populous counties have more people demanding goods and services and thus supporting more jobs. Small communities apparently can't generate enough demand to keep their own labor force busy, while larger communities don't have enough people to provide for all of their own demands and thus must import labor.
You can download similar data for your own county at the BEA website; I've also uploaded my own back-of-the-envelope spreadsheet for your enjoyment here.