The spread of the Spanish language took almost the same trajectory as English. If you can read this page and you are a citizen of the United States, it means you can speak English even though you do not come from the United Kingdom. Well, the spread of dominant languages always start with the dominant culture trying to impose their ways on a minority. The question that you would be asking yourself is whether the cheap literature review United States is a minority. The simple answer is that at one point, the US, by then called just America was a minority inhabited by Native Indians.
We can trace the entrance of the Spanish language into the country to 1492 when Christopher Columbus, an Italian voyager, arrived in Guanahani, which he later named San Savador to the chagrin of the powerless locals. I mean, how does a foreigner come to your land and decide that the name you use for the place is mouthful and decides to get an easier name? The locals loathed Columbus and thought he was the worst kind of monster to ever step foot on their land. He arrived in a voyage sponsored by Spain, then called ‘Crown of Castile.’ His job was to locate new lands that they could conquer, which was the only thing that Europeans were good at then. The real reason he was sent was to discover India for the spices he had heard of; however, even when he landed in Guanahani, he thought he was in India, perhaps because of the Red Indians he met and thought were not worth the land.
In Guanahani, Columbus found something that he never thought he would get outside Europe. He found gold, silver and human communities that were far more complex than any European city he had visited. While his hosts, in all their niceties, thought he was a kind visitor and showed him all their treasures. They walked him around, Columbus all this while making up his mind about the new land. During this time, he also decided that he did not need to make any friends with the locals.
When he sent word back about his discoveries, the Castile Empire was impressed and decided it was time to send more voyages, so they sent three more. The arrival of these voyages established a Spanish colonial power in America. The Spaniards, having won their war against the Muslims in the Iberian Peninsula, set out on a mission to impose Christianity everywhere they went. In their effort to spread the new religion, they thought they could use Latin, Spanish and the indigenous languages simultaneously in South and Central America. With the mix of languages, the Spanish language was slowly getting dominance and developing various forms from the speakers. When the colonies finally liberated themselves years later, the various dialects of Spanish language had already taken root as the dominant languages and could not be shed off as bearing colonial artefacts. That is the Spanish language spread to Latin America.