While immigrant labor stimulated northern economic growth, immigrant families transformed the urban landscape. They crowded into houses and apartments and built ethnic institutions, including synagogues and convents—visible indicators of the growing diversity of northern cities. While most native-born Protestants applauded economic growth, cultural diversity aroused anxieties. Anti-Catholicism and anti-Semitism flourished in the 1830s and 1840s. Crude stereotypes portrayed Jews as manipulative moneylenders and Catholic nuns and priests as sexually depraved. Ethnic groups also battled stereotypes. Irishmen, for example, were often pictured as habitual drunkards.

Still, rising immigration did not deter rural Americans from seeking economic opportunities in the city. Native-born white men often set out on their own, but most white women settled in cities under the supervision of a husband, landlady, or employer. African Americans, too, sought greater opportunities in urban areas. In the 1830s, more blacks joined Philadelphia’s vibrant African American community, attracted by its churches, schools, and mutual aid societies. New Bedford, Massachusetts, a thriving whaling center, recruited black workers and thus attracted fugitive slaves as well.

Yet even as cities welcomed many migrants and immigrants, newcomers also faced dangers. Racial and ethnic minorities regularly faced discrimination and hostility. Physical battles erupted between immigrant and native-born residents, Protestant and Catholic gangs, and white and black workers. Criminal activity flourished as well, and disease spread quickly through densely populated neighborhoods. When innovations in transportation made it possible for more affluent residents to distance themselves from crowded inner cities, they moved to less congested neighborhoods on the urban periphery. Horse-drawn streetcar lines, first built in New York City in 1832, hastened this development.

By the 1840s, economic competition intensified, fueling violence among those driven to the margins. Native-born white employers and workers pushed Irish immigrants to the bottom of the economic ladder, where they competed with African Americans. Yet Irish workers insisted that their whiteness gave them a higher status than even the most skilled blacks. When black temperance reformers organized a parade in Philadelphia in August 1842, white onlookers—mostly Irish laborers—attacked the marchers, and the conflict escalated into a riot.

Americans who lived in small towns and rural areas regularly read news of urban violence and vice. Improvements in printing created vastly more and cheaper newspapers while the construction of the first telegraph in 1844 ensured that news could travel more quickly from town to town. Tabloids wooed readers with sensational stories of crime, sex, and scandal. Even more respectable newspapers reported on urban mayhem, and religious periodicals warned parishioners against urban immorality. In response to both a real and a perceived increase in crime, cities replaced voluntary night watchmen with paid police forces.