The Mexican Frontier, 1821–1846 The Mexican Frontier, 1821–1846 The Mexican Frontier, 1821–1846: The American Southwest Under Mexico by historian David J. Weber is a history of the part of Mexico's north and northwest that became part of the United States after the Mexican–American War. The book examines territories on the northern frontier of Mexico, including what is now Arizona, California, New Mexico, and Texas, in the twenty-five years after Mexico gained its independence from Spain. Weber emphasizes the role of Mexicans in the region through this period of transition, particularly before and during the Texas war of independence, as well as exploring the region
Mexican–American War could not be released from its obligations. The US was released from all obligations of Article XI five years later by Article II of the Gadsden Purchase of 1853. The 1848 Treaty of Guadalupe Hidalgo ended the war and enforced the Mexican Cession of the northern territories of Alta California and Santa Fe de Nuevo México to the United States. Mexico acknowledged the loss of what became the State of Texas and accepted the Rio Grande as its northern border with the U.S. The losses amounted to one-third of its original territory from its 1821 independence. Before the secession of