factors that affect the tendency of people to migrate. Simply put, Lee holds that
potential migrants will consider two sets of criteria when making a decision about
migration. The “push” factors are negative characteristics of the place of origin of
migrants and might include high unemployment rates, poor living conditions, a
limited number of potential spouses, and numerous other conditions. The “pull”
factors represent the positive qualities of the potential destination, such as a higher
standard of living, being closer to family members who have already migrated,
greater political or religious freedom, etc. These considerations may work either
individually or in concert to motivate a person or group to migrate. The incentives
to migrate must overcome thefriction of distancebetween two locations, which
represents the costs of moving, both in terms of actual financial investment as well
as the time required to migrate. In general, the “friction” associated with migration
increases as a function of distance, but many other factors besides just distance
may increase the friction; the necessity of crossing an international border, for
example, even if located nearby, functions to inhibit migration.
Migration has played a large role in both human tragedy and progress. Migra-
tion to the New World, both voluntary and forced, completely changed theland-
scapeof that region between the 16th and 20th centuries, leading to development
of vast stretches of wilderness, but often with catastrophic consequences for
indigenous peoples. The United States isfrequently cited as a “nation of immi-
grants,” a statement that is quite true in that except for Native Americans, who
comprise about two percent of the population, all citizens or their ancestors
Migration 229Turner Thesis
Sometimes called the Frontier Thesis, the Turner Thesis is named after Frederick Jackson
Turner (1861–1932), a professor of history who first proposed his theory in 1893 at a profes-
sional meeting of historians. Turner’s concept of American identity focuses on the role of the
frontier in sculpting a unique American character. Turner argued that the interaction
between the untamed wilderness and “civilization” along the frontier’s margin had conferred
a special set of qualities on the American identity, in that the struggle to master the wilder-
ness beyond the frontier provided confidence, strength, and rugged self-reliance. As the line
of the frontier advanced westward over the course of the century and a half of American his-
tory, these characteristics intensified. Americancultural identity, although initially derived
from the European continent, deepened the qualities that differentiated it from its origins,
as the boundary shifted to the west. Turner was strongly influenced byenvironmental
determinism, and some of his critics suggest that his ideas were designed to justify Ameri-
canimperialismin the Pacific Basin and elsewhere. Although his theory has been largely
abandoned by historians, it represented one of the first efforts to articulate the foundations
of an American identity, a topic that continues to generate debate today.