When one considers the extent of the world frontier in process of occupation during the last century, the persuasive effect of its call upon the older world for labor and capital, the coloring of the whole world by the natural resources it has unearthed and the institutions it has developed, its conquest can hardly be considered as second in influence to any factor of the time. Naturally it is not intended to present here even a basis for its study. The fundamental factors and the different systems can be accurately enough described in general terms, but the differences in their operation are less precise than has been indicated; private corporations exist in Siberia, state public improvements in the United States. Many of the similarities produced everywhere by frontier conditions have been neglected. The attempt has been merely to indicate some of the tendencies fostered by different types of control. The differences between the various frontiers, resulting from race and geography, which in many cases explain the different types of organization or modify their working, have been left untouched. The problem is immense, its study is one for generations. Yet some things he who runs may read. Even a partial acquaintance with the main features of all cannot but render the work of each statesman and historian more effective in his own particular task. Some things will be understood only when no frontier, as we know it, exists. Yet even while we are in the current, we have accumulated some material, and it would seem to be contributory negligence not to use it. It must be patent that one must be honest or must pay for it. Can we not secure some rough idea of which system of approach has resulted in the greater justice between the creditor and debtor section, and what is justice? Has community control of its development or creditor control been most economical and most effective? Has exploitation to produce local capital any justification? What system has called to the task the greater proportion of ability? Would the United States have fared better under a system by which Webster, Clay, and Calhoun would have devoted to moulding the transportation system the genius they spent in bolstering up public credit? Which system has been the most responsive to the needs of the situation, and which has stimulated the greatest amount of public virtue, and which has been most easily manipulated for selfish advantage?