The Viceroyalty of New Spain (Spanish: Virreinato de la Nueva España) was an integral territorial entity of the Spanish Empire, established by Habsburg Spain during the Spanish colonization of the Americas. It covered a huge area that included territories in North America, Central America, Asia and Oceania. It originated after the fall of Mexico-Tenochtitlan, the main event of the Spanish conquest, which did not properly end until much later, as its territory continued to grow to the north. It was officially created on 8 March 1535 as a viceroyalty (Spanish: virreinato), the first of four viceroyalties Spain created in the Americas. Its first viceroy was Antonio de Mendoza y Pacheco, and the capital of the viceroyalty was Mexico City, established on the ancient Tenochtitlan.
It included what is now Mexico plus the current U.S. states of California, Nevada, Colorado, Utah, New Mexico, Arizona, Texas, Oregon, Washington, Florida and parts of Idaho, Montana, Wyoming, Kansas, Oklahoma and Louisiana; as well as the southwestern part of British Columbia of present-day Canada; plus the Captaincy General of Guatemala (which included the current countries of Guatemala, the Mexican state of Chiapas, Belize, Costa Rica, El Salvador, Honduras, Nicaragua); the Captaincy General of Cuba (current Cuba, Dominican Republic, Puerto Rico, Trinidad and Tobago and Guadeloupe); and the Captaincy General of the Philippines (including the Philippines, the Caroline Islands, the Mariana Islands and the short lived Spanish Formosa in modern day northern Taiwan).
The political organization divided the viceroyalty into kingdoms and captaincies general. The kingdoms were those of New Spain (different from the viceroyalty itself); Nueva Galicia (1530); Captaincy General of Guatemala (1540); Nueva Vizcaya (1562); New Kingdom of León (1569); Santa Fe de Nuevo México (1598); Nueva Extremadura (1674) and Nuevo Santander (1746). There were four captaincies: Captaincy General of the Philippines (1574), Captaincy General of Cuba, Captaincy General of Puerto Rico and Captaincy General of Santo Domingo. These territorial subdivisions had a governor and captain general (who in New Spain was the viceroy himself, who added this title to his other dignities). In Guatemala, Santo Domingo and Nueva Galicia, these officials were called presiding governors, since they were leading real audiences. For this reason, these hearings were considered "praetorial."
There were two great estates. The most important was the Marquisate of the Valley of Oaxaca, property of Hernán Cortés and his descendants that included a set of vast territories where marquises had civil and criminal jurisdiction, and the right to grant land, water and forests and within which were their main possessions (cattle ranches, agricultural work, sugar mills, fulling houses and shipyards) . The other estate was the Duchy of Atlixco, granted in 1708, by King Philip V to José Sarmiento de Valladares, former viceroy of New Spain and married to the Countess of Moctezuma, with civil and criminal jurisdiction over Atlixco, Tepeaca, Guachinango, Ixtepeji and Tula de Allende. King Charles III introduced reforms in the organization of the viceroyalty in 1786, known as Bourbon reforms, which created the intendencias, which allowed to limit, in some way, the viceroy's attributions.