We investigate the proposition that the health of migrants does not constitute a random sample of the health of the sending region using data from the Panel Study of Income Dynamics on internal migration within the United States. Panel data is crucial, as it enables us to observe geographic mobility as well as the health of the migrant prior to migration. We find that, for men and women below 60 years of age, a move from the middle to the bottom of the health distribution reduces mobility by 32-40% and 12-18%, respectively. Nonrandom attrition from the panel implies that these estimates are lower bounds. By contrast, we find evidence that, among older people, there is higher mobility at the top and bottom of the health distribution than there is at the middle. We consider two explanations for this: first that elderly persons may migrate to be closer to a family network once they fall ill, and second that non-random attrition may also be causing an upwards bias in the estimated effect of illness on mobility.
