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
Mexican War of Independence rule until the Hidalgo revolt of 1810. Elites in Mexico City in the seventeenth century did force the removal of a reformist viceroy, the Marqués de Gelves, following an urban riot in 1624 fomented by those elites. He attempted to eliminate corrupt practices by creole elites as well as rein in the opulent displays of the clergy's power, but ecclesiastical authorities in conjunction with creole elites mobilized urban plebeians to oust the viceroy. The crowd was reported to shout, "Long live the King! Love live Christ! Death to bad government! Death to the heretic Lutheran [Viceroy Gelves]! Arrest the viceroy!"