Plains Indians made trails near the banks of the Rio Grande that Spanish explorers used in the 18th century. Early settlers later built a road close to the riverbank connecting their ranches. Later called the Military Road, it ran from Brownsville to Laredo, linking frontier forts and stagecoach and mail lines. During the Civil War, it served as an inland route for cotton shipping, and parts of it also were used for cattle drives. In the 1870s, it served as the military telegraph road between Forts Brown and McIntosh. Paved by the 1940s, the highway became a significant part of the region's history.