It was the frontier of Europe in a very real sense.

Bowen, BS. 2002. Groove-billed Ani (Crotophaga sulcirostris), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online.

In short, atthe frontier the environment is at first too strong for the man.

Nol E and RC Humphrey. 2012. American Oystercatcher (Haematopus palliatus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology.

Moving westward, the frontier became more and more American.

With the frontier gone, where was he to find the basis for democracy in contemporary civilization?

It was across this frontier that French troops and their Indian allies put pressure on colonial Massachusetts, Connecticut, and New York throughout the 17th and 18th centuries, which ended only with the defeat of France in the Seven Years War.

FJ Turner, Frontier Thesis - University of Michigan …

At the Atlantic frontier one can study the germs of processes repeated at each successive frontier. We have the complex European life sharply precipitated by the wilderness into the simplicity of primitive conditions. The first frontier had to meet its Indian question, its question of the disposition of the public domain, of the means of intercourse with older settlements, of the extension of political organization, of religious and educational activity. And the settlement of these and similar questions for one frontier served as a guide for the next. The American student needs not to go to the "prim little townships of Sleswick" for illustrations of the law of continuity and development. For example, he may study the origin of our land policies in the colonial land policy; he may see how the system grew by adapting the statutes to the customs of the successive frontiers. He may see how the mining experience in the lead regions of Wisconsin, Illinois, and Iowa was applied to the mining laws of the Rockies, and how our Indian policy has been a series of experimentations on successive frontiers. Each tier of new States has found, in the older ones, material for its constitutions. Each frontier has made similar contributions to American character, as will be discussed farther on.

Excerpts from writings of Frederick Jackson Turner, 1890s-1920s

Loria, the Italian economist, has urged the study of colonial life as an aid in understanding the stages of European development, affirming that colonial settlement is for economic science what the mountain is for geology, bringing to light primitive stratifications. "America," he says, "has the key to the historical enigma which Europe has sought for centuries in vain, and the land which has no history reveals luminously the course of universal history." He is right. The United States lies like a huge page in the history of society. Line by line as we read from west to east we find the record of social evolution.

Frederick Jackson Turner - Wikipedia

As England's main Indian ally, the Iroquois posed a unique threat to New France, and the French felt obliged to try to neutralize Iroquois military power during much of the 17th century.

View Essay - Frontier Thesis from HISTORY 110 at Columbia

In Turner's thesis, the American frontier is portrayed as the line between settled and Indian lands, which runs roughly north to south and which continually recedes westward.