Answer:
It changed many things, especially on who was the victor to lead the world.
For many years none of the countries in the western hemisphere was seen as a superpower because the superpower was rather Spain, which is odd since Spain is in Europe. What made Spain the superpower in the west is the many colonies the country still owned in the beginning of the 20th century such as Guam, Cuba, and Puerto Rico. The United States going to war with Spain was almost the same way of Mexico going to war with the United States, And, unlike Mexico, the US won the war with a treaty signaling that Spain or any other country from Europe should no longer conquer land in the Americas, which lead to Spain surrendering all of its American lands to the US.
With the loss of the lands, it was assured that the US will be the world’s next superpower. Not only because the US benefitted much from the treaty, but the fact that the country has defeated two different superpowers in its existence. The first one was England, the one that was too relentless on keeping the grip on the American colonies that even took them to their defeat by the colonists and two other allies. The second one is, of course Spain, the one that did basically nothing to get the US declaring war on them (USS Maine, a ship of the US navy was sunk because of an engine failure, but the people believed it was sunk by Spain). Also, due to the war against Spain, the US still possesses Puerto Rico to this day, a territory that almost half of Americans think it’s not part of the United States.