The Mexican Frontier, 1821–1846 published by other historians. This work was supplemented by additional primary materials which he discovered in the archives that allowed him to delve further into certain areas. "The Mexican Frontier" examines the southwestern United States, specifically the areas now known as Arizona, California, New Mexico, and Texas, in the twenty-five years between Mexico's independence from Spain and the beginning of the Mexican–American War. This resulted in the transfer of control of the border areas to the United States. In the early days of the Republic of Mexico, these areas comprised its northern border, including the territories of Alta California and
Declaration of Independence of the Mexican Empire the National Autonomous University of Mexico are working on a system of preservation and exhibition of historical documents in order to permanently exhibit the act in the near future. Declaration of Independence of the Mexican Empire The Declaration of Independence of the Mexican Empire () is the document by which the Mexican Empire declared independence from the Spanish Empire. This founding document of the Mexican nation was drafted in the National Palace in Mexico City on September 28, 1821, by Juan José Espinosa de los Monteros, secretary of the Provisional Governmental Board. Three copies of the act were executed. One