US birthrates are dropping. This Iowa county is an exception.

Still, in an era of falling fertility throughout the United States, Sioux County offers a vision of immigration as a growth engine. Sioux Center’s growth has been propelled by immigrants and their children, primarily from Spanish-speaking countries. But the growing Hispanic presence here has also met nativist resistance. In the 2020 census, Sioux County was one of the only nonmetropolitan counties in Iowa that grew. Sioux Center, the largest town, has nearly 9,000 residents today, up from 7,000 in 2010. Its rural industries and services draw in foreign and U.S.-born...