San Diego County's population declined by about 5,300 residents in 2025, the first year-over-year drop since 2021, following a 65% drop in foreign arrivals attributed to the Trump administration's immigration crackdown. Net international migration fell from 17,655 to 6,135. The county saw the sixth-largest numeric population decline among U.S. counties, and every one of California's 58 counties saw a drop in foreign-born arrivals, with 30 counties experiencing overall population declines. Economists warn that continued immigration restrictions could harm labor force availability and economic growth.