The relocation of Europeans across the North Atlantic during the first decade and a half of the twentieth century was the culmination of the longest-lived and most widely documented transoceanic migration of modern times. This enormous population transfer was a great human drama, a major international demographic shift, and a massive historical experiment in cultural transformation during a period of unprecedented globalization. This migration was also a complex and powerful travel business containing both risks and rewards for its three fundamental participants: the movers, the moved, and the sovereign authorities on either side of the borders being traversed. Prior studies have not adequately explained this business nor appreciated the extent to which the various strategies for dealing with its associated risks were crucial, largely congruent, and self-reinforcing elements of the overall migration process.