Immigrants are helping to give some struggling cities a new lease on life. In Hartford, CT; Newark, NJ; Stockton, CA; and Trenton, NJ, more than one in five residents are now foreign-born. In general, cities with smaller foreign-born populations are more likely to be distressed: In the average distressed city, 15 percent of the population is foreign-born; in all other quintiles, the average is between 18 and 19 percent.