Southwest border encounters, documented monthly by U.S. Customs and Border Protection (CBP), measure all enforcement actions along the 1,954-mile U.S.-Mexico border. This comprehensive metric includes apprehensions (87%) and inadmissibility determinations (13%) across nine border sectors. Data categorization includes demographic profiles (country of origin, age, family status), entry methods, and processing dispositions. Title 42 expulsions (health-related) and Title 8 apprehensions (immigration law) are tracked separately. Seasonal patterns show peak activity in spring months, with varying intensity by sector (highest in Rio Grande Valley, Del Rio sectors). Enforcement resources include 19,500 Border Patrol agents, technology assets (sensors, cameras, drones), and physical barriers (approximately 700 miles of primary fencing). The metric correlates with regional economic conditions, political instability in source countries, and U.S. immigration policy changes. Data includes recidivism rates (25%), asylum claims, and processing center capacities, informing resource allocation, policy effectiveness, and international cooperation efforts.