A core theme throughout Turner’s essay is the frontier as the foundation for a unique American national character, distinct from European roots. According to Turner, “the frontier is the line of most rapid and effective Americanization” (4) where the wilderness environment transformed European immigrants into rugged Americans. He argues that the “primitive” conditions of the frontier enabled the continual rebirth and reinvention of American society in contrast to Europe’s more static established structures. Turner portrays the wilderness environment as at first too demanding for European settlers. He presents the gradual western expansion as the learned adaptation of the settlers, arguing that they adapted by adopting useful Indigenous methods for traversing the land. This process of shedding and adapting old customs under frontier constraints led to personal flexibility and fluid identity.

In Turner’s view, the isolation from coastal settlements increased the frontier’s “particularly American tendencies” as it distanced itself from European norms (6). Turner frequently appeals to this notion of Americans rebirthed through overcoming the challenges posed by wild frontiers, cultivating energetic self-reliance in place of cautious European conventions. He argues that studying the frontier explains what is uniquely “American” about America’s history and character, as the frontier imparts its democratizing influence throughout the country (4).