El Camino Real (literally, "the royal road") is the oldest and longest historical trail in the Western Hemisphere. The transportation link has, through the centuries, been called various names, including El Camino Real de Tierra Adentro (literally, "the road to the interior" because the U.S. frontier was seen as the country interior to Mexico), the King's Highway and the Royal Highway. It became a transportation lifeline that helped integrate Spanish and European culture in the Southwestern U.S.
This trail was the first European inland transportation route in the continental U.S. and is considered the forerunner of the interstate highway system because it symbolizes the importance of regional and national road networks for political, social, defense, and economic gain. The roadway, which was in part composed of Indian footpaths and buffalo trails, began at Mexico City in 1540 and was developed over the next half century.
- The Central Branch was the most direct route from Mexico City, Mexico to Santa Fe, New Mexico a distance of about 1,600 miles.
- The El Camino Real - Eastern Branch extended from Vera Cruz, Mexico through Texas, Louisiana, Mississippi, and Alabama, ending its 2,400-mile route in St. Augustine, Florida.
- The Royal Road : El Camino Real from Mexico City to Santa Fe , Christine Preston, Douglas J. Preston, Jose Antonio Esquibel, 1998, U. of New Mexico Press.