Plains Indians made trails near the banks of the rio Grande that were used by Spanish explorers in the 18th century. Early settlers built a road close to the river bank connecting their ranches. Later called the Military Road, it ran from Brownsville to Laredo, linking frontier forts and stagecoach and mail lines. An inland route for cotton shipping during the Civil War, parts of it also were used for cattle drives. It served as the military telegraph road between Forts Brown and McIntosh in the 1870s. Paved by the 1940s, the highway is a significant part of the region's history. (1997)