International migration has flowed and ebbed in two long waves over the last two hundred years. The major determinants of international migration have been the economy and the state. The economic forces impinging on migration are demography, technology, the level of wages, and geographical proximity, transportation, and communications. The state is the confluence of social and political forces within countries which define, encourage or curtail, and regulate movement across borders. The lesson of the nineteenth-century migration system is that states created it or allowed it to happen. They also always had the power to end it, and they eventually did. The huge break in the history of migration which accompanied the era of the world wars points to the decisive power of the state to control migration and, by extension, the direction of economic development itself. The present article reviews the major phases of the history of modern migration in order to put the present crossroads in perspective.