Danny Hayes examines research (pdf) on it:
The facilities that release the most toxic emissions (measured by number of pounds) are the most likely to locate near a downwind border. So what’s leading polluters to make these decisions? The authors acknowledge that their data can’t say anything about the process that brings pollution facilities to downwind borders. But they suggest two possibilities.
One is that state policy makers encourage it. For instance, Texas would surely want the economic development and tax revenue that would come from a new manufacturing plant. But the state could probably do without the resulting toxic emissions. So one option would be to encourage a manufacturer to locate on Texas’ northern border, where the wind tends to blow across the Red River into Oklahoma.
Alternatively, companies might decide on their own to build a facility in a location where pollution would be carried across state lines. Doing so might reduce the effectiveness of NIMBY, or not-in-my-backyard, activism.
The Dish 