Across the globe, industrialization set people in motion with the lure of jobs. Between the Civil War and World War I, over 25 million immigrants entered the United States. The American working class became truly global, including not only people of African and Western European descent but also Southern and Eastern Europeans, Mexicans, and Asians. In 1900, census takers found that more than 75 percent of San Francisco and New York City residents had at least one parent who was foreign-born.

In the new industrial order, immigrants made an ideal labor supply. They took the worst jobs at low pay, and during economic downturns tens of thousands returned to their home countries, reducing the shock of unemployment in the United States. But many native-born Americans viewed immigrants with hostility, through the lens of racial, ethnic, and religious prejudices. They also feared that immigrants would take more coveted jobs and erode white men’s wages. For immigrants themselves, America could be disorienting, liberating, and disappointing.