What do we call the largest phase of imperialism in us history

Explanation:

American imperialism comprises policies aimed at extending the political, economic, and cultural influence of the United States over areas beyond its boundaries. Depending on the commentator, it may include military conquest, gunboat diplomacy, unequal treaties, subsidization of preferred factions, economic penetration through private companies followed by intervention when those interests are threatened, or regime change.[4][page needed]

The policy of imperialism is usually considered to have begun in the late 19th century.[5] The federal government of the United States has never referred to its territories as an empire, but some commentators refer to it as such, including Max Boot, Arthur Schlesinger, and Niall Ferguson.[6] The United States has also been accused of neocolonialism, sometimes defined as a modern form of hegemony, which uses economic rather than military power, and sometimes used as a synonym for contemporary imperialism.