The population of Providence, R.I., has barely held even since 2020. Had it not been for some 8,300 immigrants who settled in Providence County, it would have shrunk by 1.3 percent by last year. Same in South Bend, Ind., where some 1,700 immigrants into Saint Joseph County barely filled a gap left by locals ditching town. Immigrants slowed demographic decline in more than 1,100 counties from 2020 to 2023, according to census estimates. Their numbers made up more than the entire growth of the population in 131 of them. The demographic reality casts immigration in a different light, not as...