Across the American landscape, a quiet arithmetic has been at work — in rental offices, classrooms, and hiring halls — as record numbers of people crossing the southern border have left measurable imprints on communities from Texas to New York. The Associated Press, working from exclusive data verified over months, has produced a rare empirical portrait of demographic change as it actually moves through a society: unevenly, concretely, and with consequences that outlast any single political moment. What emerges is not an argument but an accounting — a reminder that the largest human movements