Immigrant ancestors of the peak years
"About one-third of all American immigrants who arrived between Jamestown and the First World War came during the 1900-1914 period to a United States being reinvented: economically, politically, and culturally. Many things often regarded as traditional parts of the “American way of life” actually were initiated or first gained prominence during this decade and a half: for example, automobiles, airplanes, radio, recorded music, telephones, motion pictures, federal income taxes, national parks, musicals, the Boy Scouts, and the World Series of baseball. Eleven million newcomers from Europe were one vital part of this profound and pivotal period. How and why they came is an important story not comprehensively elucidated by histories of individual immigrant groups over longer time intervals, nor developed thoroughly by analytical studies from within traditional academic disciplines."
Business of Transatlantic Migration (Introduction)