El Camino Real de Tierra Adentro is the earliest Euro-American trade route in the United States. Tying Spain's colonial capitol at Mexico City to its northern frontier in distant New Mexico, the route spans three centuries, two countries, and 1,600 miles. El Camino Real was blazed atop a network of footpaths that connected Mexico's ancient cultures with the equally ancient cultures of the interior West. El Camino Real began in Mexico City. As the "Royal Road of the Interior Lands," the frontier wagon road brought Spanish colonists into today's New Mexico. Once travelers crossed the arid lands above Ciudad Chihuahua, they followed the wide Rio Grande Valley north into New Mexico. This book is a reference guide for the rich heritage evident in the many place names that align with El Camino Real de Tierra Adentro, or Royal Road. To that end, this book, both a travel guide and a place name sourcebook, is aimed at recounting the history of the Camino Real and its significance to our national story as well as the associated histories of Spain and Mexico