In the majority of the States we find a moderate degree of enthusiasm for historic sites; sufficient at least to afford them adequate protection and insure their preservation. Some far-seeing societies are alive to the significance of the historic highways that penetrated the American wilderness and are marking them with permanent milestones. A notable example of this is the marking of the “Old Santa Fe Trail” by the people of Kansas—a movement in which Colorado and New Mexico might well join. The determination of Coronado’s line of march has occupied the attention of careful students for many years and we may hope at some future time to see positively determined sites on this historic way permanently marked and recorded. The significance of our frontier has not been recognized except in social science. Fortunately its advance is well marked. The movement of the military frontier is preserved in monuments and military post buildings throughout the west. Court-house corner stones record the advance of law and order, we may say, the legal frontier—its earliest landmarks in the far west in the form of prominent trees, high bridges, and projecting beams, being pointed out with modest pride by the early inhabitants as memorials of Judge Lynch and the Vigilantes. The progress of education and religion is marked by record stones upon the public edifices devoted to these uses. The importance of all these records should be more generally recognized. Whenever a modern structure is to succeed an antiquated public building, the old record stone should invariably be preserved and reset in some conspicuous place. Future students of history and social sciences will see in these the ancient shore-lines of American social development. The military-religious frontier of the Spanish-American civilization moved from south to north. Its limits are marked by the quaint old mission churches of New Mexico and California. Some of these buildings are still in the hands of the Church, in use and kept in repair. Some are on the sites of long-abandoned Pueblo Indian villages, at the mercy of the elements and the vandals. In California these splendid old landmarks are being cared for by the organized efforts of thinking people and we need give ourselves no concern as to their preservation. Not so in New Mexico. Here we have ruins of five of the oldest historic structures of which any vestiges remain on the soil of the United States, all dating from the first half of the 17th century; all abandoned yet nobly resisting the elements. These are the ruins of the mission churches at the abandoned pueblos of Pecos in western San Miguel county; Giusewa in the Jemez valley near Perea; Tabira, popularly known as “Gran Quivira” in northeastern Socorro county, and Abo and Cuaray in eastern Valencia county.