Causes of Migration

Historical Context & Motivation

Human migration is as old as humanity itself, yet systematic study of its causes only began in the late nineteenth century when geographer Ernst Georg Ravenstein published his influential "Laws of Migration" in 1885. Ravenstein observed census data from England and Wales, noting regularities in who moves, how far they move, and why. His work established that migration is not random but is instead governed by identifiable economic, social, and environmental factors that can be analyzed at multiple geographic scales. Before Ravenstein, migration was often treated as an incidental consequence of conquest or famine rather than a phenomenon with predictable structural causes. The intellectual tradition he inaugurated continues to shape how geographers, demographers, and policymakers understand population movement today.

The central question that migration theory seeks to answer is deceptively simple: Why do people move? Understanding the causes of migration requires analyzing an interplay of economic incentives, political conditions, environmental pressures, social networks, and cultural ties that operate simultaneously across local, regional, and global scales. For the AP Human Geography exam, you need to distinguish among different categories of push and pull factors, connect them to broader theoretical frameworks such as Ravenstein's laws and Lee's model, and apply these concepts to real-world case studies ranging from the Great Migration of African Americans to contemporary refugee crises.

Core Principles & Definitions

At the foundation of migration studies lies a set of interrelated concepts that organize our understanding of why populations relocate. Migration itself is defined as the permanent or semi-permanent change of residence across a significant boundary, whether that boundary is a neighborhood line, a state border, or an international frontier. Geographers distinguish migration from other forms of spatial mobility—such as commuting, tourism, or seasonal circulation—by emphasizing the relative permanence and distance involved. The analytical power of migration studies comes from recognizing that every migration event is simultaneously shaped by conditions at the place of origin, conditions at the destination, obstacles or facilitators encountered along the way, and the individual characteristics of the migrant.

Visual Explanation: The Push-Pull Model

The diagram above captures the essential insight of Lee's framework: migration is never the result of a single factor operating in isolation. Every origin possesses both negative attributes that push people away and positive attributes that retain them—a farmer in rural Guatemala, for example, may face severe drought (push) but also have deep family and community ties (retain). Similarly, every potential destination presents both attractive pull factors—such as higher wages in the United States—and repelling factors like anti-immigrant discrimination. Intervening obstacles such as international borders, immigration policies, physical distance, and the financial cost of relocation determine whether the desire to migrate translates into actual movement. Finally, personal factors—age, education level, wealth, marital status, and individual risk tolerance—explain why two people facing identical push and pull factors may make entirely different decisions about whether to migrate.

How Migration Causes Operate Across Scales

Categories of Push and Pull Factors

Migration causes can be organized into four broad categories that appear repeatedly on the AP Human Geography exam: economic, political, environmental, and social/cultural. Understanding these categories and being able to identify specific examples within each one is essential for both multiple-choice and free-response questions. Each category can function as either a push or pull factor depending on the context, and in most real-world migration events, factors from multiple categories interact simultaneously.

Ravenstein's Laws and Their Modern Relevance

Ravenstein's original "laws" remain foundational for the AP exam, though some have been modified by subsequent research. His key observations include: most migrants move only short distances; migration proceeds in stages (step migration); each current of migration produces a compensating counter-current; long-distance migrants tend to move to major commercial or industrial centers; urban residents are less migratory than rural residents; and economic factors are the primary cause of migration. While Ravenstein's emphasis on economics remains broadly valid, modern migration scholarship has increasingly recognized the role of political violence, environmental change, and social networks—factors that Ravenstein's Victorian-era analysis could not fully account for. The concept of step migration—where a migrant moves from a rural village to a nearby town, then to a regional city, and finally to a major metropolis—remains a powerful descriptive tool for understanding rural-to-urban migration streams in the developing world.

Types of Migration: Voluntary, Forced, and Internal

The AP exam expects students to classify migration not only by cause but also by the degree of choice involved and by the geographic scale of movement. The distinction between voluntary migration and forced migration is fundamental, though in practice many migrations occupy a gray area between the two. A Central American family fleeing gang violence but also seeking economic opportunity exemplifies this complexity. Geographers also distinguish between internal migration (movement within a country's borders) and international migration (movement across national borders), each with distinct causes, legal frameworks, and consequences.

Worked Example: Analyzing the Great Migration

Consider a common AP FRQ prompt: "Explain the push and pull factors that caused the Great Migration of African Americans from the rural South to northern cities between 1916 and 1970." The following worked example models how to structure a thorough response using the push-pull framework.

Strengths & Limitations of Migration Theories

No single theory fully explains the complex causes of migration. The AP exam tests your ability to evaluate different theoretical perspectives and recognize their applicability to specific scenarios. The push-pull framework is intuitive and widely applicable, but it tends to reduce migration to a series of individual cost-benefit calculations, potentially overlooking structural forces like colonialism, global capitalism, or institutional racism that shape migration patterns at a systemic level. Each major theory offers distinct analytical strengths while also carrying recognizable blind spots.

Connections to Advanced Theory & Contemporary Issues

The causes of migration connect to several broader themes in AP Human Geography, including globalization, urbanization, political geography, and cultural change. As you encounter these topics in other units, you will see how migration functions as both a cause and a consequence of larger geographic processes. For instance, the study of transnational migration—where migrants maintain strong social, economic, and political ties to both their origin and destination countries—challenges the traditional assumption that migration is a one-time, one-direction event. Transnational migrants send remittances back to their home communities, vote in elections across borders, and circulate cultural practices between societies, making migration a key mechanism of globalization.

Looking ahead in the AP curriculum, migration causes will reappear when you study urban geography (rural-to-urban migration driving megacity growth), political geography (refugee crises and sovereignty debates), cultural geography (diffusion of languages and religions through diaspora), and agriculture (labor migration sustaining commercial farming). Mastering the causes of migration now provides an analytical foundation that will serve you across the entire course.

Practice Problems

Causes of Migration — Summary