Internal migration is both shaped by environmental forces and a generator of new environmental pressures. Yet scholarly debates often treat “environmental migration” as a narrow subset of hazard-driven mobility, while treating internal migration more generally as a response to economic incentives and social networks. This article synthesizes classic and contemporary theories to show how environmental factors are embedded throughout internal migration systems. Drawing on push–pull theory, the Harris–Todaro expected wage framework, human-capital and life-course approaches, the New Economics of Labor Migration, social-capital perspectives, political ecology, social-ecological resilience, and spatial equilibrium models, we develop an integrative account of how environmental exposure, sensitivity, and adaptive capacity interact with household decision-making and meso-level network structures, and how these interactions aggregate into regional migration regimes. Methodologically, we ground the analysis in a narrative review of canonical works and recent advances in environmental mobility studies, spatial modeling, and climate-risk research. We argue that environmental variables operate as structural “background” conditions that alter relative prices, risks, and opportunities, refracting through institutions and social networks to shape the scale, direction, timing, and selectivity of internal migration. We also highlight feedbacks: internal migration can relieve or amplify local environmental stress through land-use change, urban congestion, and infrastructure transitions. The article closes with implications for research design and policy, including the need to model endogeneity between environment, livelihoods, and mobility; to integrate fine-scale environmental data with longitudinal microdata; and to treat migration not only as a symptom of environmental stress but also as a potential component of adaptation strategies.

Internal migration, environmental factors, push–pull

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