As Spain's frontier expanded, links were maintained between the northernmost settlements and Mexico City. As the vast area developed, a network of roads, or caminos reales, grew between major settlements, presidios, and missions. Originally blazed along game trails for military use, over time these roads provided a path for civilian settlers, trade and supply trains and, late in the colonial period, a postal service.
Today, the routes of these trails are being sought and mapped. Remnants are being designated as El Camino Real de los Tejas National Historical Trail.