This article appears in the Summer 2015 issue of The American Prospect magazine. Subscribe here . A mysterious thing happened on the way to the widely projected meltdown of American cities in the last quarter of the 20th century. Instead of collapsing, many of our largest and hardest-hit cities have rebounded and flourished, confounding critics and social scientists alike. Why did these cities experience renaissance rather than ruin? Or, to paraphrase the late University of Pennsylvania historian Michael Katz, “Why didn’t American cities burn?” More broadly, what accounts for the remarkable decline of violent crime in the United States and the return of urban vibrancy? Although certainly not the only factor, immigration deserves attention as part of the answer for the nation’s crime decline and urban revitalization. Immigrants have gravitated to many of the urban areas that were most distressed 40 years ago and have contributed to their economic revival...