Cigarette Smoking and Selective Migration: Are Tobacco Control Policies Less Effective in Rural America?

In 1956, 52% of urban men and 42% of rural men smoked cigarettes. By 2010, while the prevalence of smoking was dramatically lower for both groups, the disparity had flipped: 24.7% of urban men and 30.6% of rural men smoked and similar patterns exist for women. This paper puts forth a new potential explanation for the observed urban/rural smoking trends: selective internal migration. Between 1950 and 2010, the share of the United States population living in an urban area increased from 64% to 81%. If relatively more educated, higher-SES individuals are driving urbanization, as seems likely from the economics literature on migration, then migration and the well-known correlation between smoking and education may generate relatively fewer urban smokers. On the other hand, if smokers are more likely to move from rural to urban areas, perhaps seeking better job opportunities, then observed disparities between urban and rural populations may be understated. If smoking is correlated with clear determinants of migration (e.g., job opportunities, education, income, etc.), then migration flows will alter the smoking composition of local areas over time.

The potential for selective migration matters for the evaluation of tobacco control policies, both overall and by location. The vast majority of studies of cigarette taxes and indoor smoking bans on smoking prevalence use repeated cross-sectional data and research designs which assume that the composition of urban and rural populations remains fixed over time. These designs typically use within-state variation in smoking prevalence to identify the effect of changes in policy on smoking prevalence. If net migration changes the smoking composition of a state or county, then the estimated effect of changes in tobacco control policy will reflect both the policy and the smoking composition change.

To address the potential for selective migration to a.) explain the change in urban/rural smoking disparity and b.) bias our understanding of tobacco control policy, I simulate a Roy model of selective migration. The model demonstrates the conditions under which migration shifts the smoking composition of a local area. Next, I merge data from the Current Population Survey's Tobacco Use Survey and Annual Social and Economic Supplement from 1993 through 2015, and I demonstrate a strongly positive correlation between smoking and migration. Finally, I estimate the effect of state-level cigarette taxes and indoor smoking bans on smoking behavior after controlling for nonrandom population movement (i.e., selective migration). My approach is to estimate the probability of migration into a given state conditional on socio-economic characteristics. The estimated probabilities then enter a control function which, in a regression of smoking on these local area policies, nets out the effect of shifting population characteristics. The result of this analysis will allow for me to decompose the within-state trend in smoking to a.) tobacco control policies, b.) selective migration.