Effects of Interstate Migration on the Geographic Distribution of Stroke Mortality in the United States

Abstract

This study examines the effects of lifetime net interstate migration on the geographic distribution of stroke mortality in the United States. National Center for Health Statistics and Bureau of the Census data were used to map the geographic distribution of age-adjusted, race-, and race/sex-specific stroke mortality rates by interstate migration status for natives, outmigrants, nonmigrants, inmigrants, and residents in the United States for 1979 to 1981. High age-adjusted stroke mortality rates were significantly clustered in the southeastern United States for both whites and blacks; in addition, for whites, low-rate states were concentrated in some Mountain and northeastern states. Migrant status did not change this large-scale pattern, but individual states showed significant migration effects, which varied in magnitude and direction. Among whites, states that benefited from migration, with markedly lower stroke mortality rates among residents than natives, included Arizona, Colorado, District of Columbia, and Florida, whereas states that suffered from migration included California, Idaho, Montana, North Dakota, Nevada, and Oklahoma. Among blacks, only Colorado showed an apparent large benefit from migration, whereas 21 states suffered from migration. Although the overall large-scale spatial distribution of resident stroke mortality rates cannot be explained by migration effects, some individual states had rates that were strongly influenced by migration. Patterns of mortality among migrant groups in Sun Belt retirement destination states probably result from differential selection effects for retirement migration in older adults. Patterns of mortality for black migrants to the North are probably influenced by "carryover" effects from their origin states.