HAZARD, Lucy Lockwood

p. xviii :

[L]ife in America has been conditioned by the perennial rebirth of the frontier. The successive frontiers present a moving picture of American life – moving geographically and chronologically from the Atlantic settlements of the 17th century to the California mining camps of the 19th century ; moving economically from the pathfinder, the trapper, to the exploiter, the land-speculator.

(The Frontier in American Literature, 1967)