Spanish colonization of the New World

The Colonial expansion under the crown of Castile was initiated by the Spanish conquistadores and developed by its administrators and missionaries. The motivations for colonial expansion were trade and the spread of the Catholic faith through indigenous conversions.

Beginning with the 1492 arrival of Christopher Columbus and continuing for over three centuries, the Spanish Empire would expand across the Caribbean Islands, half of South America, most of Central America and much of North America (including present day Mexico, Florida and the Southwestern and Pacific Coastal regions of the United States). It is estimated that during the colonial period (1492–1832), a total of 1.86 million Spaniards settled in the Americas and a further 3.5 million immigrated during the post-colonial era (1850–1950).

In the early 19th century, the Spanish American wars of independence resulted in the emancipation of most Spanish colonies in the Americas, except for Cuba and Puerto Rico, which were finally given up in 1898, following the Spanish–American War, together with Guam and the Philippines in the Pacific. Spain's loss of these last territories politically ended the Spanish rule in the Americas.

The Catholic Monarchs Isabella of Castile, Queen of Castile and her husband King Ferdinand, King of Aragon, pursued a policy of joint rule of their kingdoms and created a single Spanish monarchy. Even though Castile and Aragon were ruled jointly by their respective monarchs, they remained separate kingdoms. The Catholic Monarchs gave official approval for the plans of Genoese mariner Christopher Columbus for a voyage to reach India by sailing West. The funding came from the queen of Castile, so the profits from Spanish expedition flowed to Castile. In the extension of Spanish sovereignty to its overseas territories, authority for expeditions of discovery, conquest, and settlement resided in the monarchy.

...
Wikipedia