INTRODUCTION. 
IMPORTANCE OF THE MEXICAN ARCHIVES. 
When we consider the close and long-standing historical connection be- 
tween Mexico and the United States, the chief cause for surprise, as regards 
the archives of Mexico, is not that they contain much material for the history 
of the United States, but rather that this material has been so little known and 
used. For more than two centuries, under the Spanish régime, a large portion 
of the territory that is now within the United States was controlled on the 
civil, military, and ecclesiastical sides by the governmental agencies at the city 
of Mexico or, more directly, by those at some more northern centre. Im- 
portant among the latter, at one time or another, were the military com- 
mandancies at Chihuahua, Arispe, Monterrey (Nuevo Leon), Monclova, Sal- 
tillo, and Matamoros, the real audiencia and the archbishopric at Guadala- 
jara, the great Franciscan missionary colleges at Querétaro and Zacatecas, 
and the intendancies at Arispe, Durango, and San Luis Potosi. It would be 
strange indeed if important records of this long period of Spanish control 
should not be preserved at the capital and also at some of these subordinate 
seats of authority. 
Since the separation of Mexico from Spain, as the result of the long revo- 
lutionary struggle from 1810 to 1821—the War of Independence—the rela- 
tions between Mexico and the United States, sometimes friendly and some- 
times otherwise, have been fully as intimate as those of the former period. 
Obviously, one side of the true story of those relations must be found, if any- 
where, in the national and local records of Mexico, just as the other side is 
to be found in the archives of the United States. 
Yet these records, for either period, have never been duly searched by 
students of the history of the United States. These considerations, supported 
by the rich finds of the few who have studied United States history in Mex- 
ican archives, justified the undertaking of the preparation of a general guide 
to the materials which they contain for this subject. The wealth of documents 
encountered in the course of the investigation has in most respects fully 
borne out the expectations. The chief general cause for disappointment, per- 
haps, will be the apparent lack of materials for the earliest period of contact 
between what are now Mexico and the United States ; for, compared with the 
great wealth of documents for later times, there is a notable dearth, so far as 
our researches have gone, of documents for the sixteenth and the early seven- 
teenth centuries. It is greatly to be hoped that this seeming lack in the Mex- 
ican archives may be supplied by those of Spain. Other special causes for 
disappointment will be the failure to find any considerable portion of the 
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