U.S. Route 380 (US 380) is an east–west United States highway that spans the states of Texas and New Mexico. Known for serving as an important regional connector rather than a long-haul route, US 380 stretches for approximately 673 miles, from San Antonio Junction, Texas (near U.S. Route 83), to San Antonio, New Mexico, where it terminates at U.S. Route 70. The route traverses a wide variety of landscapes, including desert basins, mountain ranges, agricultural valleys, and booming suburbs, especially around the Dallas–Fort Worth metroplex.

In Texas, US 380 is a vital corridor linking growing communities across the northern part of the state. Towns and cities such as Denton, McKinney, and Greenville have seen explosive growth, and US 380 has increasingly served as a commuter and freight route in this fast-developing corridor. Its importance in North Texas has led to ongoing discussions and projects aimed at widening and upgrading the highway to meet modern traffic demands. As it moves west, the route becomes more rural, crossing open plains and oil-rich regions before entering the rugged terrain of West Texas.

Upon crossing into New Mexico, US 380 takes on a more scenic and remote character. It passes through the Lincoln National Forest and the historic town of Lincoln—closely tied to Billy the Kid lore—before eventually merging with US 70 in the Rio Grande Valley. Portions of the route through New Mexico offer sweeping views and access to outdoor recreation areas, making it a pleasant drive for road trippers and history buffs alike.