The population of the United States has diverse sources: territorial acquisition through conquest and colonialism, the slave trade, and voluntary immigration, which has been the greatest instrument of population expansion and has been central to the transition in the nineteenth and twentieth centuries from a rural-agricultural to an urban-industrial society. Recognition of the need for labor to develop and expand economic activity has been central to policies and laws enabling mass immigration. Many Americans, too, value the memory of immigrant ancestors, and are sentimentally inclined to immigrant strivings. Alongside the embrace of immigration has been the perception that immigration destabilizes social order, cultural coherence, job markets, and political alignments. In some observers that recognition has been animated by racist appraisals of various immigrant peoples and by nativism, a general dislike of people and things foreign to Americans. The century and a half of American nationhood has been characterized by both support for openness to immigration and embrace of a cosmopolitan formulation of American identity and for restrictions and assertions of belief in a core Anglo-American national character. The book traces three massive waves of immigration from the mid-nineteenth century to the present, and analyses the nature of immigration as a purposeful, structured activity, attitudes supporting or hostile to immigration, policies and laws regulating immigration, and the nature of and prospects for assimilation. This second edition takes account of the dramatic developments since 2011, including the crisis along the southwestern border and the intense conflict over illegal immigration"--