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Population Distribution

From the beginning, humanity has been unevenly distributed over the land and this pattern was in-tensified during the twentieth century. Whether urban or rural, populations tend to cluster in certain areas because, as you will recall from earlier discussions, much of the Earth is unsuitable for human occupancy (see maps below). To handle contrasts of this type on maps, geographers use measures of population distribution—the locations on the Earth's surface where individuals or groups (depending on the scale of the map) are concentrated —and the density of the population figured as the number of people per unit area of land.

Figure below shows patterns of population distribution for the world using the dot method. It shows that the world's three largest population concentrations all lie on the Eurasian landmass —East Asia, South Asia, and Europe—each associated with a major civilization. It also reminds us that the overwhelming majority of the world's population inhabits the Northern Hemi-sphere.

East Asia, centered on China but extending to Korea and Japan, contains about one-quarter of the world's population—nearly 1.3 billion in China alone. The map shows that the population is concentrated toward the coast with ribbon-like extensions found on the basins and lowlands of China's major rivers. The great majority of people in East Asia are farmers.

India lies at the center of the South Asian concentration with extensions to Pakistan, Bangladesh, and the island of Sri Lanka. This is one of the greatest concentrations of people on Earth with about 1.5 billion people. It is a confined region (the Himalaya Mountains on the north and the desert west of the Indus River in Pakistan) with a rapidly growing population. By almost any estimate, the capacity of the region to support this population has been exceeded. As in East Asia, the majority are farmers.

Europe, the third-ranking population cluster, also lies in Eurasia but at the opposite end from China. This cluster contains about 700 million people, which puts it in a class with the South Asian concentration, but the similarity ends there. In Europe, unlike East and South Asia, terrain and environment are not as closely related to population distribution. Another contrast lies in the fact that the majority of the European population live in cities and towns, leaving the rural country-side more open and sparsely populated. These contrasts with the East and South Asian clusters reflect the impact of the Industrial Revolution on Europe over the last 200-plus years.

Population Density

Population density can be measured on the basis of several different criteria, revealing contrasting aspects of a country's demography. Figure below illustrates density via the isopleth method. The data in Table 2-1 on page 52 in your textbook provides density measures of a few countries. One must examine such data with caution, however, since the high cost and organizational challenges of census taking often produce unreliable data. Arithmetic and physiologic population densities are the two most common approaches. These two methods become more meaningful and useful when compared with each other.

WHERE AND WHY PEOPLE MOVE

Humans have always been mobile. Throughout history humans have sought new frontiers and the search still continues today. For more than 90 percent of human history there were hunter-gatherers, a practice that required frequent relocation. Such movement is called migration and while the reasons for such movement are different today, human mobility has actually increased in modern times.

Human mobility is of central interest in human geography because it is an inherently spatial process. Human movement speeds the diffusion of ideas and innovations. It intensifies spatial interaction and transforms whole regions. And as you will see in this chapter, it is often closely linked to environmental conditions.

Why People Move

Many factors stimulate the migration process. They include armed conflict, economic conditions (real or perceived), political strife, cultural circumstances (such as linguistic or religious differences), environmental change (growing more common today), and technological advances (which makes information about destinations more easily obtainable and movement easier). Migration today occurs for various reasons but those listed are the principle ones.

Migrants move on the basis of their perceptions of particular destinations, taking into consideration both direction and distance. Direction, like location, can be viewed in two ways: absolute and relative. Absolute direction refers to astronomically determined direction and thus is what we think of as compass direction. Relative direction is more perceptual and often imprecise, W in the ewe of the Sunbelt. The residents of North Dakota, for example, would agree that it lies to the south and that Florida is part of the Sunbelt, but not everyone would agree that Utah is also. Different people have different perceptions.

Distance, like direction, can be measured in both absolute and relative terms. Absolute distance is the physical distance between two points usually using kilometers or miles; it can be read on maps using the scale of the map. Absolute distance does not change. Relative distance-measured not in linear terms such as miles or kilometers, but in term such as cost or time-bas different meanings for different people and cultures. It can change due to, say, a new method of transportation or the discovery of a shorter route. Research has shown that people's perception of both distance and direction can be greatly distorted and that distance particularly affects the accuracy of migrants perception of their destinations.

Forms of Human Mobility

Mobility of all kinds is one of the defining characteristics of a culture. The great majority of people have a daily routine that takes them through a regular sequence of short moves that geographers call activity (or action) space. The magnitude of activity space varies in different societies, and American society is the world’s most mobile. Technology has greatly expanded activity spaces, particularly in the wealthier, more developed countries.

There are three general types of movement recognized by geographers and others who study human mobility. (cyclic movement—movement that has a closed route—defines your activity space. When you go to daily classes or a job you are participating in cyclic movement. If your trip involves a lengthy period of residency after your arrival—such as temporary relocation for college attendance or service in the armed services—you engaged in periodic movement. Both cyclic and periodic movements occur in many forms. Finally, migratory movement describes human movement from a source to a destination without a return journey, and is the most significant form of movement discussed in this chapter. A society’s mobility is measured as the sum of cyclic, periodic, and migratory movement of its population.

Patterns Of Migration

Rarely does migration take place in a single step, rather it usually takes place in stages. Rural-to-urban movement occurs in steps, often to a small community and then to a lager one and perhaps eventually to an even larger one in a region of more favorable environmental conditions. Migrants also tend to relocate repeatedly after reaching the end of their destination. Early immigrants to America, for example, often first settled in regions where relatives or friends were located, moving "West" after a time seeking land of their own or better opportunity, often moving several times before settling permanently. Some, of course, found the new surroundings not to their liking and returned cast or perhaps to their original source region in a counter or return migration. Almost all migration flows have this aspect.

Factors Of Migration

The decision to migrate usually results from a combination of conditions and perceptions that tend to induce people to leave their abodes, Geographers who study human migration call the negative conditions and perceptions push factors. The positive conditions and perceptions that effectively attract people to new locale from other areas are called pull factors. Push factors are likely to be perceived more accurately than pull factors, since people are more likely to be familiar with their place of residence (source) than the locale to which they are moving. Push factors include individual considerations ranging from work or retirement conditions to weather and climate. Pull factors tend to be more vague and many migrants move on the basis of excessively positive images and expectations regarding their destinations.

Our final look at the reasons people move focuses on the luxury of choice and the fear of compulsion. These may be classed as voluntary and forced migrations. There are different cases within each of these categories and it is not always easy to make a clear determination. In the case of the millions of Europeans who came to the Americas, most were seeking opportunity and better living conditions. These same motives carried others far from Europe to the African and Asian colonies. The prevailing force was the pull of opportunity and thus for the most part, emigrants from Europe left by choice.

Several of the worlds largest migration streams have been forced migrations, which result from the imposition of power by stronger peoples over weaker ones. By far the most important of these was the Transatlantic slave trade, which carried tens of millions of Africans from their homes to the Americas, with enormous loss of life. From 12 million to over 30 million Africans were sold into slavery (see Figure below) and nothing in human history compares to the Atlantic slave trade. Both source and destination regions were affected, with the African sources being socially and demographically devastated for generations. Forced counter migration continues today when governments send back migrants caught entering their countries illegally.

Permanent Relocation

The past five centuries have witnessed human migration on an unprecedented scale, much of it generated by events in Europe. The voluntary migration of Europeans to the New World, the migration of Europeans to their overseas colonial empires (these two migrations may have totaled 75 million between 1835 and 1935), and the forced migration of Africans to the Americas, are among migration streams that have transformed the world. The immense impact of the forced migration of Africans during the slave trade on both sides of the Atlantic sets it apart from all the other migrations.

When early humans began migrating from Africa to Eurasia, Australia, and the Americas, they faced only natural boundaries. Rivers and mountain ranges may have presented barriers, but they did not stop the inexorable march of human migration. For today’s migrants, political boundaries, not natural ones, form the most difficult obstacles. Agencies that monitor the annual stream of human migration use the world’s political framework to keep track of migrants. Those who cross international borders are external migrants and those who relocate within their national boundaries are internal migrants. In any given year, internal migrants greatly outnumber external migrants. However, it is the external migrants who change countries’ vital statistics, affect their economies, and often influence their politics.

External migrations took Europeans to America and other parts of the world; the arrival of the Europeans, in turn, caused other people to move. External migrations (authorized movements and organized resettlements, as well as refugee movements) usually occur after wars. Following World War II, Germans migrated westward from their homes in Eastern Europe and millions of migrants left Europe altogether to go to the United States.

Internal migration involves relocation within a country. Such movements can also produce significant population shifts, even though the migrants do not cross any international borders. Internal migrations, involving major population shifts, have occurred in the former Soviet Union, the United States, China, and other large countries. Such movements are usually easier to accomplish because no inter-national borders are crossed. For the same reason, the numbers of people moving is more difficult to determine, at least in most countries.

We noted earlier that Americans are the world’s most mobile people. Etched on the U.S. population map are the effects of two historic internal migrations; the westward movement of the population as a whole, and the northward migration of black Americans from the rural South to the urban North. The West is still a major migration destination as can be seen in Figure below. In the United States, the North-east and the Midwest have been losing population for decades, while the South and West have been gaining.

Controlling Migration

Migration control and its attendant problems have become hot issues around the world. Efforts to restrict migrations are nothing new; media coverage, democratic debate, and political wrangling only make it seem so. China’s Great Wall was built in part as a barrier to emigration, as was the Berlin Wall and the fences along the Rio Grande—all evidence of the desire of governments to control the movement of people across their borders. Physical as well as legal barriers are placed in the way of migrants, but few countries have succeeded in controlling immigration effectively.