Climate Variability and Internal Migration in the United States, 1970 – 2010

Climate change affects human populations globally. While demographic literature on climate and migration focuses on lower- and middle-income contexts or natural disasters in higher-income settings, less acute environmental variability also influences migration in affluent areas. This paper examines these relationships in the United States. We combine county-level net migration rates (NMRs) and census data from 1970 to 2010 and link them to high-resolution climate records. We then assess the impact of climate variability on NMRs using fixed-effects models. We find that precipitation and temperature anomalies decreased the overall NMRs, but these effects were moderated by historical climate, metropolitan status, economic structure, and migrants’ age. Particularly, historically-warmer and nonmetropolitan counties experienced larger heat-induced declines in NMRs than cooler and metropolitan counties. Additionally, nonmetropolitan and historically-warmer counties experienced more out-migration of the younger generation (ages 15–64) during warm spells, while nonmetropolitan counties witnessed a less sharp decline in NMRs among the older generation (ages 65+). Meanwhile, precipitation and temperature anomalies reduced NMRs among both age groups in recreation counties, with weaker effects in manufacturing counties. These results highlight the importance of environmental change for population dynamics in high-income settings and its varied impacts on migration across the demographic and socioeconomic spectrum.