Mexican Cession Mexican Cession, with considerable local autonomy punctuated by several revolts and few troops sent from central Mexico, in the period from 1821–22 after independence from Spain up through 1846 when U.S. military forces seized control of California and New Mexico on the outbreak of the Mexican–American War. The northern boundary of the 42nd parallel north was set by the Adams–Onís Treaty signed by the United States and Spain in 1821 and ratified by Mexico in 1831. The eastern boundary of the Mexican Cession was the Texas claim at the Rio Grande and extending north from the headwaters of the Jojo
Declaration of Independence of the Mexican Empire 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 was destroyed in a fire in 1909. The other two copies are in the Museo Historico de Acapulco Fuerte de San Diego in Acapulco and in the General Archive