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 in his home to discuss whether it was better to obey or to revolt against a tyrannical government, as he defined the Spanish colonial government in Mexico. Famed military leader Ignacio Allende was among the attendees. In 1810 Hidalgo concluded that a revolt was needed because of injustices against the poor of Mexico. By this time Hidalgo was known for his achievements at the prestigious San Nicolás Obispo school in Valladolid (now Morelia), and later service there as rector. He also became known as a top theologian. When his older brother died in 1803, Hidalgo took over as priest for