For your additional question in the comment of the last answer (I’m not sure if you need it)
Why might the Age of American Imperialism be a very controversial topic in US history?
There are pros and cons to American imperialism which explains why it is controversial. A pro for example is that the US expands territory and with more land brings more power. It provides access to many resources and items that puts the country ahead of other less Developed countries. . Imperialism also gives a boost to the economy.. additionally, states brings technology, industries, government ideals, and privileges American citizens have to these territories.
However, that being said, there is the flip side of the coin. Cons that follow American imperialism may include views that say imperialism kills the tradition of the indigenous peoples, and they lose their identity and tradition. In many cases, the territories’ own people grow to discriminate against what is local and originally of their own native culture.
, it can be debated that the ownership of territories is not necessary. Territories can be expensive to keep, and the US is already quite expansive.