Answer: The term frontier has been defined in various ways. Webster’s International Dictionary, in 1890, described it as “that part of a country which fronts or faces another country or an unsettled region;…extreme part of a country.” In the 19th century it was statistically classified as an area having no fewer than two but no more than six European inhabitants per square mile (fewer than one to just over two Europeans per square kilometer). The United States Census Bureau defined areas with lower population densities as “unsettled” and on this basis marked the frontier line on a series of maps for each decade. Thus, areas on the frontier were no longer the exclusive domain of explorers, missionaries, and trappers, but settled homesteads were relatively rare and widely dispersed.
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